(19) TZZ ¥ _T

(11) EP 2 663 826 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Date of publication and mention (51) Int Cl.: of the grant of the patent: F41A 3/26 (2006.01) F41A 3/64 (2006.01) 16.05.2018 Bulletin 2018/20 F41A 3/70 (2006.01) F41A 3/84 (2006.01) F41A 3/72 (2006.01) F41A 5/18 (2006.01) (2006.01) (2006.01) (21) Application number: 12701610.3 F41A 5/26 F41A 11/00 F41A 5/24 (2006.01) F41A 17/64 (2006.01) F41A 17/00 (2006.01) F41A 19/10 (2006.01) (22) Date of filing: 13.01.2012 F41A 19/42 (2006.01) F41A 15/14 (2006.01) F41A 19/13 (2006.01)

(86) International application number: PCT/US2012/021368

(87) International publication number: WO 2012/097334 (19.07.2012 Gazette 2012/29)

(54) FEUERWAFFE ARME À FEU

(84) Designated Contracting States: (74) Representative: Freeman, Jacqueline Carol AL AT BE BG CH CY CZ DE DK EE ES FI FR GB WP Thompson GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO 138 Fetter Lane PL PT RO RS SE SI SK SM TR London EC4A 1BT (GB)

(30) Priority: 14.01.2011 US 201161433115 P (56) References cited: 16.08.2011 US 201161524138 P EP-A1- 0 055 690 EP-A1- 1 479 997 EP-A1- 1 596 151 EP-A2- 2 045 561 (43) Date of publication of application: CH-A- 37 247 CH-A- 199 224 20.11.2013 Bulletin 2013/47 DE-A1- 3 707 925 DE-A1-102007 034 670 FR-A- 1 362 361 GB-A- 166 579 (73) Proprietor: Armwest, LLC GB-A- 525 429 GB-A- 604 348 Prescott, Arizona 86305 (US) US-A- 1 588 887 US-A- 1 907 164 US-A- 1 946 388 US-A- 2 088 268 (72) Inventors: US-A- 2 096 028 US-A- 2 365 306 • SULLIVAN, Leroy James US-A- 2 376 466 US-A- 2 462 119 Prescott, Arizona 86305 (US) US-A- 2 482 880 US-A- 2 756 640 • WATERFIELD, Robert Lloyd US-A- 2 910 332 US-A- 3 090 148 Prescott, Arizona 86303 (US) US-A- 3 090 149 US-A- 3 330 183 • OSTROWSKI, Alan H. US-A- 3 346 982 US-A- 3 366 011 Prescott, Arizona 86305 (US) US-A- 3 795 173 US-A- 3 990 348 • LATULIPPE, JR., Paul N. US-A- 5 448 940 US-A- 5 909 002 Chino Valley, Arizona 86323 (US) US-A1- 2005 262 752 US-A1- 2008 092 733 • EYSSAUTIER, Hyunjung Samuel US-A1- 2010 095 833 US-B1- 6 829 974 Prescott, Arizona 86303 (US) US-B1- 8 316 756

Note: Within nine months of the publication of the mention of the grant of the European patent in the European Patent Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the Implementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). EP 2 663 826 B1

Printed by Jouve, 75001 PARIS (FR) 1 EP 2 663 826 B1 2

Description [0007] The document EP1479997 (A1) discloses a which has a stock and a removable barrel. The stock has TECHNICAL FIELD a stock housing and a recess for the barrel. The barrel has at least one pin. The recess has an aperture for the [0001] One or more of the embodiments relate gener- 5 pin. There is a groove round the pin. A locking device ally to , and more particularly for example, to a acts with the groove. The extent to which the pin projects firearm configured to facilitate a quick barrel change and from the barrel may be adjustable. having features which enhance the reliability thereof. BRIEF SUMMARY BACKGROUND 10 [0008] A firearm according to the invention is defined [0002] Semi-automatic and fully automatic firearms by the wording of claims 1 - 15. are well known. Semi-automatic firearms shoot one bullet [0009] In accordance with embodiments further de- each time that the trigger is pulled. Fully automatic fire- scribed herein, features are provided that may be advan- arms continue shooting as long as the trigger is pulled 15 tageously used in one or more firearm designs. Some of and they have not exhausted their ammunition. Fully au- these embodiments are covered by the claims and form tomatic firearms are typically capable of relatively high part of the present invention whereas other embodiments rates of fire, i.e., cyclic rates. For example, the M16 and are not covered by the claims and hence do not form part the M4 have a nominal cyclic rate of 700 to 950 rounds of the present invention. According to an embodiment, a per minute. 20 firearm canhave a backbone, abarrel, aswinging wedge, [0003] Because fully automatic firearms are capable and a barrel latch. The barrel latch can be in mechanical of such high cyclic rates, they are prone to a variety of communication with the swinging wedge such that mov- problems. For example, sustained fully automatic fire can ing the barrel latch will move the swinging wedge. The result in barrel overheating. Barrel overheating is partic- barrel latch can have a first position and a second position ularly problematic when high capacity magazines, such 25 and the swinging wedge can be configured to maintain as SureFire’s 60 round and 100 round magazines, are attachment of the barrel to the backbone when the barrel being used. High capacity magazines allow longer peri- latch is in the first position and can be configured to re- ods of sustained fire since fewer changes are lease the barrel from the backbone when the barrel latch required to fire a given number of rounds. Fewer maga- is in the second position. zine changes provide less time for the barrel to cool.30 [0010] According to an embodiment, a firearm can Thus, the barrel, as well as other parts of the firearm, can have a carrier, a backbone configured to guide the be subjected to increased heat. bolt carrier, a lower receiver within which the bolt carrier [0004] Often, the ability to keep firing is limited by barrel is at least partially disposed wherein the barrel is attached overheating. When the barrel of a firearm overheats, ac- to the backbone, a barrel latch attached to the backbone, curacy of the firearm is substantially reduced. Further 35 a barrel configured to disengage from the backbone overheating of the barrel can result in malfunction of the when the barrel latch is pushed, a trigger block assembly firearm. For example, cartridges chambered into an over- configured to drop into the lower receiver, a gas piston heated barrel can detonate prematurely, i.e., cook off, having a plurality of piston rings configured to only rotate particularly in firearms. If the barrel is over- substantially in unison with one another, an operating rod heated sufficiently it can deform, thereby resulting in a 40 configured to move in response to movement of the gas catastrophic failure of the firearm. piston and configured to move the bolt carrier when a [0005] Even after the barrel has returned to an accept- is discharged, a metered gas port disposed out able operating temperature, the firearm may be unusa- of the barrel for metering gas from the barrel to the gas ble. The barrel and/or other components of the firearm piston,a springguide having a main spring disposed ther- may have been permanently damaged. Changing the 45 eon for biasing the bolt carrier in a forward position, an barrel of a contemporary firearm such as the M16 or M4 anti-bounce weight at least partially contained within the takes a substantial amount of time and is not generally spring guide, a bolt carried by the bolt carrier, an extractor performed in the field. When the firearm is unusable due attached to the bolt, two springs disposed within the bolt to overheating and while the barrel is being changed, a for biasing the extractor toward a closed position of the soldier or police officer cannot shoot the firearm and is 50 extractor, a bar inhibiting separation of the lower receiver thus undesirably vulnerable to attack. and the backbone when the main spring is compressed, [0006] The inability to shoot a firearm can have disas- a firing pin disposed within the bolt, a firing pin retaining trous consequence in battlefield and police situations. pin configured to facilitate removal of the firing pin and The inability to shoot has resulted in loss of life in such configured to transfer forward movement of the bolt car- instances. Therefore, it is desirable to provide systems 55 rier to the firing pin to cause a cartridge to fire, a hammer for facilitating the quick change of the barrel of a firearm assembly disposed within the lower receiver and having and for otherwise enhancing the reliability and utility of a hammer and a link with one end of the link attached to the firearm, for example. the hammer and another end of the link attached to the

2 3 EP 2 663 826 B1 4 lower receiver such that the hammer has a rearward po- barrel latch,and a pin attached tothe barrel. The swinging sition that is below the bolt when the bolt is in a rearward wedge can be configured to facilitate attachment of the position and the hammer has a forward position where barrel to the backbone via the pin such that moving the the hammer strikes the firing pin when the bolt is in a barrel latch allows the barrel to detach from the back- forward position and wherein the link is configured such 5 bone. that the hammer has sufficient throw to travel over a last [0016] According to an embodiment, a device can have round stop as the hammer moves from the rearward po- a trigger block assembly for a firearm. The trigger block sition tothe forward position, a takedown lever configured assembly can be configured to drop into the firearm. to inhibit separation of the backbone and the lower re- [0017] According to an embodiment, a device can have ceiver, the takedown lever having a safety lock pin to10 a piston for a gas operated firearm. Two protrusions can inhibit inadvertent movement of the takedown lever, a be formed upon the piston and configured to stop rear- charging handle configured to move rearward to move ward movement of the piston when the firearm is dis- the bolt carrier from an uncocked position to a cocked charged. position, a dust cover configured to open partially to allow [0018] According to an embodiment, a device can have the charging handle to move rearward, a gas port flash 15 a recoil or drive spring configured to be compressed by suppressor configured to guide the barrel during mating rearward movement of a bolt carrier when a firearm is of the barrel to the backbone, and a stock having a hor- discharged, a spring guide for limiting movement of the izontal groove formed therein. The groove can be con- drive spring, and an anti-bounce weight defined by at figured to inhibit horizontal movement of a user’s hand. least a portion of the spring guide. The anti-bounce [0011] According to an embodiment, a firearm can20 weight can be configured to inhibit bouncing of a bolt have a bolt carrier, a backbone configured to guide the carrier of the firearm. bolt carrier, a lower receiver within which the bolt carrier [0019] According to an embodiment, a device can have is at least partially disposed attached to the backbone, a a lower receiver for a firearm, a bolt having a forward barrel latch attached to the backbone, a barrel configured position and a reward position, a firing pin disposed sub- to disengage from the backbone when the barrel latch is 25 stantially within the bolt, and a hammer assembly dis- pushed, a trigger block assembly configured to drop into posed within the lower receiver. The hammer assembly the lower receiver, and a hammer assembly disposed can have a hammer and a link. One end of the link can within the lower receiver and having a hammer and a link be pivotally attached to the hammer and another end of with one end of the link attached to the hammer and an- the link can be pivotally attached to the lower receiver, other end of the link attached to the lower receiver such 30 such that the hammer has a rearward position that is that the hammer has a rearward position that is below below the bolt when the bolt is in the rearward position the bolt when the bolt is in a rearward position and the and the hammer has a forward position where the ham- hammer has a forward position where the hammer strikes mer strikes the firing pin when the bolt is in a forward the firing pin when the bolt is in a forward position. The position.The link canbe configured such thatthe hammer link can be configured such that the hammer has suffi- 35 has sufficient throw to travel over a last round stop as cient throw to travel over a last round stop as the hammer the hammer moves from the rearward position to the for- moves from the rearward position to the forward position. ward position. [0012] According to an embodiment, a device can have [0020] According to an embodiment, a device can have a bolt carrier for a firearm and a backbone configured to a stock for a firearm, a butt formed on a distal end of the at least partially guide the bolt carrier as the bolt carrier 40 stock, and a generally horizontal groove from in the butt. moves forward and backward during a firing cycle of the The generally horizontal groove can be configured to in- firearm. The bolt carrier can be not completely contained hibit vertical movement of a hand when grasping the butt. within the backbone. [0021] According to an embodiment, a gas operated [0013] According to an embodiment, a firearm can firearm can have a barrel, a gas port formed in the barrel, have a lower receiver, a backbone attached to the lower 45 a gas system, and a metered gas port not disposed in receiver, and a bolt carrier. Movement of the bolt carrier the barrel. The metered gas port can be configured to can be constrained by the backbone and not constrained meter gas from the barrel to the gas system. The metered by the lower receiver. gas port can tend to maintain a substantially uniform [0014] According toan embodiment, a device cancom- quantity of gas to the gas system as the gas port enlarges prise a bolt carrier for a firearm. The bolt carrier can hav- 50 due to wear. ing a generally tubular upper portion, a generally rectan- [0022] According to an embodiment, a device can have gular lower portion, and a waist interconnecting the upper an extractor for a firearm. The extractor can have a closed portion and the lower portion. The upper portion can be position and an open position. Two springs can bias the substantially longer than the lower portion. extractor toward the closed position. The extractor can [0015] According to an embodiment, a firearm can55 be sufficiently wide to be biased by the two springs. have a backbone, a barrel removably attached to the [0023] According to an embodiment, a device can have backbone, a barrel latch attached to the backbone, a a drive spring for a firearm and a bolt carrier. The bolt swinging wedge in mechanical communication with the carrier can have a forward position and a rearward posi-

3 5 EP 2 663 826 B1 6 tion. The drive spring can bias the bolt carrier in the for- [0031] The rear v-block bears on and centers the body ward position. A bar can be configured to be pulled for- diameter of the barrel extension while the top 120° of the ward by the bolt carrier as the bolt carrier chambers a flange of the barrel extension fits up into a locking groove cartridge. The bar can be configured to inhibit takedown in that V-block. The close fit of the flange and locking of the firearm when the bolt carrier is in the rearward 5 groove combined with the upward pull of the swinging position thereof and the drive spring is compressed. wedge on the barrel cross pin holds the barrel centered [0024] According to an embodiment, a device can have in the V-blocks, locks the barrel to the backbone and anbackbone fora firearm, a lowerreceiver for the firearm, securely blocks any fore and aft movement of the barrel and a takedown lever. The takedown lever can have a breech in relation to the backbone structure. first position and a second position. When the takedown 10 [0032] Forlongitudinal heatexpansion the barrel slides lever is in the first position separation of the backbone fore or aft in the front v-block and the swinging wedge from the lower receiver is facilitated. When the takedown follows that motion without releasing its wedging force. lever is in the second position separation of the backbone [0033] For radial heat expansion the two upper arms from the lower receiver is inhibited. A safety lock pin can of a "Y" shaped yoke fit around both sides of the barrel inhibit inadvertent movement of the takedown lever from 15 and have a cross pin fastened through them across the the first position to the second position and can inhibit top of the barrel. The ends of the cross pin extend beyond inadvertent movement of the takedown lever from the the outer sides of the two arms so that the 2-armed swing- second position to the first position. ing wedge pulls upward on the two ends of the cross pin. [0025] According to an embodiment, a device can have In the crotch of the yoke an adjustable set screw bears a charging handle for a firearm and a dust cover. The 20 on the bottom of the barrel and is factory adjusted to push dust cover can be configured to open approximately 7° downward on a flanged threaded tube compressing high to allow the charging handle to move rearwards as the force spring washers holding the yoke and cross pin firearm is cocked. downward with an initial force of approximately 317.52 [0026] According to an embodiment, a device can have kg (700 pounds). As the approximately 25.4 mm (1") bar- a firing pin and a firing pin retaining pin configured to25 rel diameter expands from the heat of firing, the angled retain the firing pin in a bolt of a firearm. The firing pin walls of the v-block force the barrel diameter downward, retaining pin can be configured to transfer forward move- the center of which moves downward about 0.1143 mm ment of a bolt carrier to the firing pin to cause the firearm (.0045 inches) while the bottom compresses the spring to discharge. washers about 0.229 mm (.009 inches) increasing the [0027] According to an embodiment, a cylinder can be 30 force to approximately 1200 pounds as the barrel tem- disposed in an backbone of a gas operated firearm. A perature reaches approximately 815.6°C (1500° F). The gas exhaust port can be formed in the cylinder for ex- barrel remains centered with no longitudinal breech hausting gas from the cylinder. A gas exhaust port flash movement. suppressor can be configured to guide a barrel to the [0034] The bottom stem of the yoke is fastened through backbone to facilitate attachment of the barrel to the35 a fore grip. backbone. [0035] To install a barrel it is lifted upward and pulled [0028] According to an embodiment, a semi-automatic rearward by its fore grip. Guide surfaces bring the barrel firearm can be configured for both closed bolt operation extension into alignment with the locking groove and the and operation. A selector mechanism can be cross pin into engagement with the swinging wedge configured to select between closed bolt operation and 40 which snaps onto the pin drawing the barrel tight upward open bolt operation of the firearm. into its V-blocks and locked into the groove. [0029] According to an embodiment, a firearm can [0036] To remove a barrel the barrel latch end of the have a bolt and can be configured for both closed bolt swinging wedge is hit downward. The same guide sur- operation and open bolt operation. The firearm can have faces that directed it into position guide it out and down- a trigger mechanism configured such that during open 45 ward on a path that prevents it from hitting or damaging bolt operation and when the bolt is rearward, pulling the a magazine. That path is also not obstructed by the weap- trigger only allows the bolt to be manually moved forward on’s bipod. when a button has been pressed. The firearm can have [0037] According to an embodiment, a firearm can a trigger mechanism configured such that during closed have a lower receiver and an backbone. The lower re- bolt operation and when the bolt is rearward pulling the 50 ceiver can be attached to the firearm via a hook pivot. trigger allows the bolt to be manually moved forward. The lower receiver can pivot downward from the firearm [0030] According to an embodiment, a firearm can whileremaining pivotally attached to thefirearm. The low- have a barrel, a lower receiver, a backbone and two V- er receiver can be detached from the backbone. blocks with a spring loaded 2-armed swinging wedge lo- [0038] These and other features and advantages of cated halfway between them and attached to the back- 55 the present invention will be more readily apparent from bone to hold the barrel pulled up tight and precisely cen- the detailed description of the embodiments set forth be- tered in the V-blocks with the flange of the barrel exten- low taken in conjunction with the accompanying draw- sion in a fore and aft locking groove in the rear V-block. ings. The scope of the disclosure is defined by the claims.

4 7 EP 2 663 826 B1 8

A more complete understanding of embodiments, as well Figure 51 is a front end view of the of as a realization of additional advantages thereof, will be Figure 1 having a section reference, according to an afforded to those skilled in the art by a consideration of embodiment; the following detailed description of one or more embod- iments. 5 Figure 5J is a cross-sectional side view taken along [0039] The firearm in accordance with the invention is line 5J of Figure 51, according to an embodiment; shown in detail in figures 34A - 36G, 50A - 75D, 75 and 76. The details of the embodiments shown in the other Figure 5K is a front end view of the machine gun of figures, in so far as not explicitly covered by the wording Figure 1 having a section reference, according to an of the claims, do not form part of the invention. 10 embodiment;

BRIEF DESCRIPTION OF THE DRAWINGS Figure 5L is a cross-sectional side view taken along line 5L of Figure 5K, according to an embodiment; [0040] 15 Figure 6A is a perspective view of the lower receiver Figure 1 is left side view of an open bolt, full auto, assembly of the machine gun of Figure 1, according semi-auto machine gun having a magazine attached to an embodiment; thereto, according to an embodiment; Figure 6B is an exploded view of the lower receiver Figure 2 is a right side view of the machine gun of 20 assembly of the machine gun of Figure 1, according Figure 1, according to an embodiment; to an embodiment;

Figure 3A is right side view of the machine gun of Figures 6C-6H are various elevational views of lower Figure 1 having the magazine removed, according receiver assembly of the machine gun of Figure 1, to an embodiment; 25 according to an embodiment;

Figure 3B is left side view of the machine gun of Figure 6I is a front end view of the machine gun of Figure 1 having the magazine removed, according Figure 1 having a section reference, according to an to an embodiment; embodiment; 30 Figure 4A is an exploded view of the machine gun Figure 6J is a cross-sectional side view taken along of Figure 1, according to an embodiment; line 6J of Figure 6I, according to an embodiment;

Figures 4B-4F are various elevational views of the Figure 6K is a front end view of the machine gun of machine gun of Figure 1, according to an embodi- 35 Figure 1 having a section reference, according to an ment; embodiment;

Figure 4G is a top view of the machine gun of Figure Figure 6L is a cross-sectional side view taken along 1 having a section reference, according to an em- line 6L of Figure 6K, according to an embodiment; bodiment; 40 Figure 7A a perspective view of a trigger block as- Figure 4H is a cross-sectional side view taken along sembly of the machine gun of Figure 1, according to line 4H of Figure 4G, according to an embodiment; an embodiment;

Figure 41 is an enlarged view taken within the section 45 Figure 7B a perspective exploded view of the trigger circle 41 of Figure 4H, according to an embodiment; block assembly of Figure 7A, according to an em- bodiment; Figure 5A is a perspective view of the lower receiver assembly of the machine gun of Figure 1, according Figures 7C-7G are various elevational views of the to an embodiment; 50 trigger block assembly of Figure 7A, according to an embodiment; Figure 5B is an exploded view of the lower receiver assembly of the machine gun of Figure 1, according Figure 8 is a perspective view of a trigger lock-out to an embodiment; mechanism of the machine gun of Figure 1 showing 55 the trigger locked out, according to an embodiment; Figures 5C-5H are various elevational views of lower receiver assembly of the machine gun of Figure 1, . Figure 9 is a perspective view of a trigger lock-out according to an embodiment; mechanism of the machine gun of Figure 1 showing

5 9 EP 2 663 826 B1 10 the trigger not locked out, according to an embodi- Figure 12L is a cross-sectional side view taken along ment; line 12L of Figure 12K, according to an embodiment;

Figures 10A-10F are various elevational views of an Figure 13A is a perspective view of a trigger block open bolt, closed bolt, semi-auto rifle having a light- 5 assembly of the semi-auto rifle of Figure 10A, ac- weight stock, according to an embodiment; cording to an embodiment;

Figure 10G is a cross-sectional side view of the rifle Figure 13B is a perspective exploded view of the of Figure 10A, according to an embodiment; trigger block assembly of Figure 13A, according to 10 an embodiment; Figure 10H is an enlarged view taken within the sec- tion circle 10H of Figure 10G, according to an em- Figures 13C-13H are various elevational views of bodiment; the trigger block assembly of Figure 13A, according to an embodiment; Figure 10I is an cross-sectional view of the semi- 15 auto rifle of Figure 10A, according to an embodiment; Figure 14A is an exploded view of an open bolt, closed bolt semi-auto rifle having a heavy duty stock, Figure 11A is a perspective view of the lower receiver according to an embodiment; assembly of the semi-auto rifle of Figure 10A, ac- cording to an embodiment; 20 Figures 14B-14F are various elevational views of the semi-auto rifle of Figure 14A, according to an em- Figure 11B is an exploded view of the lower receiver bodiment; assembly of the semi-auto rifle of Figure 10A, ac- cording to an embodiment; Figure 14G is a top view of the semi-auto rifle of 25 Figure 14A having a section reference, according to Figures 11C-11H are various elevational views of an embodiment; the lower receiver assembly of the semi-auto rifle of Figure 10A, according to an embodiment; Figure 14H is a cross-sectional side view taken along line 14H of Figure 14G, according to an embodiment; Figure 11I is a top view of the lower receiver of the 30 semi-auto rifle of Figure 10A having a section refer- Figure 14I is an enlarged view taken within the sec- ence, according to an embodiment; tion circle 141 of Figure 14H, according to an em- bodiment; Figure 11J is a cross-sectional side view taken along line 11J of Figure 11I, according to an embodiment; 35 Figure14J is atop view of thesemi-auto rifleof Figure 14A having a section reference, according to an em- Figure 12A is a perspective view of the lower receiver bodiment; assembly of the semi-auto rifle of Figure 10A, ac- cording to an embodiment; Figure 14K is a cross-sectional side view taken along 40 line 14K of Figure 14J, according to an embodiment; Figure 12B is an exploded view of the lower receiver assembly of the semi-auto rifle of Figure 10A, ac- Figure 14L is an enlarged view taken within the sec- cording to an embodiment; tion circle 14L of Figure 14K, according to an em- bodiment; Figures 12C-12H are various elevational views of 45 the lower receiver assembly of the semi-auto rifle of Figure 15A is a top view of the semi-auto rifle of Fig- Figure 10A, according to an embodiment; ure 14A having a section reference, according to an embodiment; Figure 12I is a top view of the lower receiver of the semi-auto rifle of Figure 10A having a section refer- 50 Figure 15B is a cross-sectional side view taken along ence, according to an embodiment; line 15B of Figure 15A, according to an embodiment;

Figure 12J is a cross-sectional side view taken along Figure 15C is an enlarged view taken within the sec- line 12J of Figure 12I, according to an embodiment; tion circle 15C of Figure 15B, according to an em- 55 bodiment; Figure 12K is a top view of the lower receiver of the semi-auto rifle of Figure 12A having a section refer- Figure 16A is an exploded view of an open bolt, ence, according to an embodiment; closed bolt full auto, semi-auto rifle/machine gun

6 11 EP 2 663 826 B1 12 having a heavy duty stock, according to an embod- an embodiment; iment; Figure 18J is a cross-sectional side view taken along Figures 16B-16F are various elevational views of the line 18J of Figure 18I, according to an embodiment; rifle/machine gun of Figure 16A, according to an em- 5 bodiment; Figure 18K is a top view of the rifle/machine gun of Figure 18A having a section reference, according to Figure 16G is a top view of the rifle/machine gun of an embodiment; Figure 16A having a section reference, according to an embodiment; 10 Figure 18L is a cross-sectional side view taken along line 18L of Figure 18K, according to an embodiment; Figure 16H is a cross-sectional side view taken along line 16H of Figure 16G, according to an embodiment; Figure 19A is a perspective view of a trigger block assembly of the rifle/machine gun of Figure 16A, ac- Figure 16I is an enlarged view taken within the sec- 15 cording to an embodiment; tion circle 161 of Figure 16H, according to an em- bodiment; Figure19B is a perspective exploded view of the trig- ger block assembly of Figure 19A, according to an Figure 17A is a perspective view of the lower receiver embodiment; assembly of the rifle/machine gun of Figure 16A, ac- 20 cording to an embodiment; Figures 19C-19H are various elevational views of the trigger block assembly of Figure 19A, according Figure 17B is an exploded view of the lower receiver to an embodiment; assembly of the rifle/machine gun of Figure 16A, ac- cording to an embodiment; 25 Figures 19I-19L are various elevational views of the trigger block assembly of Figure 19A, according to Figures 17C-17H are various elevational views of an embodiment; lower receiver assembly of the rifle/machine gun of Figure 17A, according to an embodiment; Figure 20 is a perspective view showing components 30 of the rifle/machine gun of Figure 16A in a closed Figure 17I is a top view of the rifle/machine gun of bolt firing configuration, according to an embodi- Figure 17A having a section reference, according to ment; an embodiment; Figure 21A is a perspective view showing compo- Figure 17J is a cross-sectional side view taken along 35 nents of the rifle/machine gun of Figure 16A wherein line 17J of Figure 17I, according to an embodiment; a hammer link has released a closed bolt sear hook to allow the hammer link to move, according to an Figure 17K is a top view of the rifle/machine gun of embodiment; Figure 17A having a section reference, according to an embodiment; 40 Figure 21B is a perspective view showing compo- nents of the rifle/machine gun of Figure 16A wherein Figure 17L is a cross-sectional side view taken along a tip of a closed bolt, open bolt arm catch captures line 17L of Figure 17K, according to an embodiment; an open bolt arm notch, according to an embodi- ment; Figure 18A is a perspective view of the lower receiver 45 assembly of the rifle/machine gun of Figure 16A, ac- Figure 22 is a perspective view showing components cording to an embodiment; of the rifle/machine gun of Figure 16A in a closed bolt firing configuration, according to an embodi- Figure 18B is an exploded view of the lower receiver ment; assembly of the rifle/machine gun of Figure 16A, ac- 50 cording to an embodiment; Figures 23A is a perspective view showing compo- nents of the rifle/machine gun of Figure 16A wherein Figures 18C-18H are various elevational views of a hammer link has released a closed bolt sear hook lower receiver assembly of the rifle/machine gun of to allow the hammer link to move, according to an Figure 18A, according to an embodiment; 55 embodiment;

Figure 18I is a top view of the rifle/machine gun of Figure 23B is a perspective view showing compo- Figure 18A having a section reference, according to nents of the rifle/machine gun wherein a tip of a

7 13 EP 2 663 826 B1 14 closed bolt, open bolt arm catch captures an open defined for the swinging wedge, according to an em- bolt arm notch, according to an embodiment; bodiment;

Figure 24 is a perspective view showing components Figures 38A-38C are various views showing a spring of the rifle/machine gun of Figure 16A in a closed 5 assembly, according to an embodiment; bolt firing configuration, according to an embodi- ment; Figures 39A-39C are various views showing a spring assembly, according to an embodiment; Figures 25A and 25B are perspective views showing components of the rifle/machine gun of Figure 16A 10 Figure 40 is a side view of a spring guide tube, ac- wherein a hammer link is held closed by a closed cording to an embodiment; bolt sear hook, according to an embodiment; Figure 41 is an end view of a spring guide insert, Figure 26 is a perspective view showing an open bolt according to an embodiment; firing mechanism of the rifle/machine gun of Figure 15 16A in a fired condition with the bolt locked and the Figures 42A-42D are various views showing a spring autosear tripped, according to an embodiment; guide cap, according to an embodiment;

Figures 27A and 27B are side views showing the Figures 43A-43D are various views showing a spring open bolt firing mechanism of Figure 26, according 20 guide, according to an embodiment; to an embodiment; Figures 44A-44D are various views showing an anti- Figure 28 is a perspective view showing an open bolt bounce spring keeper, according to an embodiment; firing mechanism of the rifle/machine gun of Figure 16A in a firing condition with the bolt unlocked, ac- 25 Figures 45A-45B are various views showing a spring cording to an embodiment; guide tube assembly, according to an embodiment;

Figures 29A and 29B are side views showing the Figure 46 is a cross-section view showing the anti- open bolt firing mechanism of Figure 28, according bounce springwith thedrive spring compressed(top) to an embodiment; 30 and with the drive spring extended (bottom), accord- ing to an embodiment; Figure 30 is a perspective view showing an open bolt firing mechanism of the rifle/machine gun of Figure Figure 47 is a cross-section view showing the spring 16A in a seared condition, according to an embodi- drive with the drive spring compressed (top) and with ment; 35 the drive spring extended (bottom), according to an embodiment; Figures 31A and 31B are side views showing the open bolt firing mechanism of Figure 30, according Figure 48 is an exploded perspective view of a spring to an embodiment; assembly, according to an embodiment; 40 Figure 32 is perspective view showing the autosear Figure 49 is perspective view showing a backbone trip bar of the rifle/machine gun, according to an em- and bolt carrier, according to an embodiment; bodiment; Figures 50A-50G are various views showing a bolt Figures 33A-33L are various views showing a selec- 45 aligned with a barrel with the backbone not locked tor cam layout according to an embodiment; to the barrel via the swinging wedge, according to an embodiment; Figures 34A-34D are various views showing barrel installation, according to an embodiment; Figures 51A-51F are various views showing a bolt 50 aligned with a barrel with the backbone locked to the Figures 35A-35D are various views showing the bar- barrel via the swinging wedge, according to an em- rel 105 and the backbone 103, according to an em- bodiment; bodiment; Figures 52A-52C show the backbone and the barrel Figures 36A-36G are various views showing a barrel 55 with various cross-sections, according to an embod- latch, according to an embodiment; iment;

Figure 37 is a drawing that shows how the curve is Figures 53A-53C show the backbone and the barrel

8 15 EP 2 663 826 B1 16 with various cross-sections, according to an embod- Figure 74 is an exploded top view of the gas metering iment; port of Figure 72, according to an embodiment;

Figures 54A-54D show the backbone and the barrel Figure 75 is a side view of a barrel positioned for with various cross-sections, according to an embod- 5 attachment to a backbone, according to an embod- iment; iment;

Figures 55A-55D show the backbone and the barrel Figure 76 is a side view of a barrel attached to a with various cross-sections, according to an embod- backbone, according to an embodiment; iment; 10 Figure 77 is a cross-sectional side view of the barrel Figures 56A-56D are various views showing barrel and backbone taken along line 77 of Figure 76, ac- release, according to an embodiment; cording to an embodiment;

Figures 57A-57D are various views showing the gas 15 Figure 78 is a cross-sectional side view showing the system, according to an embodiment; barrel and backbone of Figure 77 exploded apart from one another, according to an embodiment; Figures 58-61 are various views an extractor, ac- cording to an embodiment; Figure 79 is a cross-sectional side view of the barrel, 20 backbone, swinging wedge, and tensioner taken Figure 62 is a cross-sectional side views of an un- along line 79 of Figure 76, according to an embodi- assembled bolt, according to an embodiment; ment;

Figure 63 is a cross-sectional side views of an un- Figure 80 is a cross-sectional side view of the barrel, assembled bolt, according to an embodiment; 25 backbone, swinging wedge, and tensioner showing the barrel removed from the backbone, according to Figure 64 is an front view of the bolt, according to an an embodiment; embodiment; Figure 81 is a cross-sectional side view of the ten- Figure 65 is a cross-sectional side view of the un- 30 sioner, according to an embodiment; assembled bolt, according to an embodiment; Figure 82 is a cross-sectional side view of the barrel, Figure 66 is a cross-sectional side views of the as- according to an embodiment; and sembled bolt, according to an embodiment; 35 Figure 83 is a chart showing which features are Figure 67 is a perspective exploded view the bolt, present on which firearm, according to embodi- according to an embodiment; ments.

Figure 68 is a perspective view the assembled bolt, [0041] Embodiments illustrating the present invention according to an embodiment; 40 according to the claims as well as embodiments not cov- ered by the scope of the wording of the claims and their Figure 69 is a flow chart showing operation of the advantages are best understood by referring to the de- firearm, according to an embodiment; tailed description that follows. It should be appreciated that like reference numerals are used to identify like el- Figure 70 is a perspective view showing two gas pis- 45 ements illustrated in one or more of the figures. ton rings positioned together such that a key of one ring is disposed within a gap of the other ring, ac- DETAILED DESCRIPTION cording to an embodiment; [0042] An improved firearm, in accordance with one or Figure 71 is a perspective view showing the two gas 50 more embodiments, has various different features that piston rings of Figure 70 exploded apart from one enhance the operation and use thereof. In accordance another, according to an embodiment; with the subject matter of the invention as claimed the barrel of the firearm can be changed quickly in the field Figure 72 is a cross-sectional side view showing the according to an embodiment. The ability to perform a gas metering port, according to an embodiment; 55 quick barrel change enhances the firepower provided by the firearm and thus enhances the utility thereof. That is, Figure 73 is a top view of the gas metering port of the number of rounds that can be fired per minute, in- Figure 72, according to an embodiment; cluding time for barrel changes, is substantially in-

9 17 EP 2 663 826 B1 18 creased. 1000 and the rifle/machine gun 8000 can [0043] According to an embodiment, the firearm can be made in 5.56 mm or 6.8 mm. be compatible with large capacity magazines. For exam- [0050] Figures 4A-4F are additional views of the ma- ple, the firearm can be compatible with 60 and 100 round chine gun 100, according to an embodiment. The ma- magazines. The firearm can be configured to withstand 5 chine gun 100 has a lower receiver or receiver assembly the heat associated with sustained fully automatic fire. 102. The receiver assembly 102 can include a grip 107 The ability to quickly change the barrel is one aspect of and a magazine well 108. how the firearm can withstand the heat associated with [0051] The backbone 103 constrains a bolt carrier 111, sustained fully automatic fire. as described herein. A charging handle 109 can be slid- [0044] Three different types of firearms are discussed 10 ably disposed between the backbone 103 and the receiv- herein. These three types are a light machine gun, a er assembly 102 so as to facilitate cocking of the machine semi-automatic (civilian) rifle, and a rifle/machine gun. gun 100 by pulling a bolt carrier 111 rearward. A spring The machine gun can fire either semi-automatic or fully guide 112 can be at least partially disposed within the automatic and fires only from an open bolt. The semi- bolt carrier 111 and can define an anti-bounce system, automatic rifle is semi-automatic only and can fire from 15 as discussed herein. either an open bolt or closed bolt. The rifle/machine gun [0052] A barrel assembly 104 can be removably de- can fire either semi-automatic or fully automatic and can tachable from the machine gun 100 (as well as from the fire from either an open bolt or a closed bolt. The rifle/ma- semi-automatic rifle 1000 (Figures 10A-10F) and the ri- chine gun fires full auto only from an open bolt and fires fle/machine gun 8000 (Figure 16A) by pressing a barrel semi-auto from either an either open bolt or a closed bolt. 20 latch 113 on the backbone 103, as discussed herein. The [0045] Each type of firearm can be made in any desired barrel 105 can have a fore grip 106. caliber. For example, each type of firearm can be made [0053] A stock 114 can be removably attachable to the in 5.56x45mm NATO or 6.8x43mm. Both 5.56x45mm receiver assembly 102. The stock 114 can be pivotally NATO and 6.8x43mm can share components. For ex- attached to the receiver assembly 102 such that the stock ample, both 5.56x45mm NATO and 6.8x43mm can gen- 25 114 can fold to either side of the receiver assembly 102. erally share all components except the barrel, bolt, and The stock 114 can be a heavy duty stock, as shown. magazine for a given type of firearm. Alternatively, the stock 114 can be a lightweight stock or [0046] The semi-automatic rifle and the rifle/machine any other type of stock. guncan firesemi-auto from either an openbolt or aclosed [0054] As shown in Figure 4A, the stock 114 can have bolt. Generally, firing from a closed bolt provides better 30 at least one generally horizontal groove 126 formed accuracy. However, it may be desirable to change to therein. The groove 126 can allow the user to better grasp open bolt firing if many shots are fired in rapid succession, the stock 114 when shooting to inhibit undesirable move- so as to reduce the likelihood of an undesirable cookoff. ment, e.g., upward movement, of the stock 114. For ex- As discussed herein, changing from open bolt to closed ample, when the stock 114 is stowed or folded along side bolt requires an extra step (such as depressing a button 35 of the receiver assembly 102, a user can grasp the grip on the selector), so as to more likely cause the user to 107 with one hand and can grasp the butt 127 of the stock consider whether or not such a change is appropriate, 114 with the other hand such that the user’s thumb is in since closed bolt operation can result in a cookoff, as one of the grooves 126 to more securely hold the firearm. discussed herein. [0055] Figures 4G-4I show a drop-in trigger assembly [0047] In the semi-automatic rifle and the rifle/machine 40 400, according to an embodiment. The trigger block as- gun, every shot is fired by a hammer. A long throw, long sembly 400 can be assembled outside of the machine travel hammer is used advantageously, as discussed gun 100. Once assembled, the trigger block assembly herein. As discussed herein, the machine gun is not fired 400 can be dropped into place in the receiver assembly by a hammer. 102, as discussed herein. [0048] Figures 1 and 2 show an open bolt machine gun 45 [0056] Figures 5A and 5B show the receiver assembly 100, according to an embodiment. The machine gun 100 102 with Figure 5B showing the trigger block assembly is capable of full auto and semi-auto fire, as selected by 400 exploded from the receiver assembly 102, according a user. The machine gun 100 fires from an open bolt. to an embodiment. The receiver assembly 102 has a re- The machine gun 100 has a magazine 101 attached ceiver sub-assembly 5101, an open bolt arm 5102, an thereto. The magazine 101 can be, for example, a 60- 50 open bolt arm sear 5103, an open bolt arm pin 5104, an round or 100-round magazine such as those sold by openbolt full auto/semi auto trigger block assembly5105, SureFire, LLC of Fountain Valley, California. a barrel latch safety 5106, a handgrip bolt 5107, a selector [0049] Figures 3A and 3B show the machine gun 100 barrel latch 5108, a closed bolt safety button assembly with the magazine 101 removed, according to an embod- 5109, a take down lever 5110, hammer link crosspin iment. The machine gun 100, as well as the semi-auto- 55 5111, a sear crosspin 5112, and a selector cam assembly matic rifle 1000 (Figure 10A) and the rifle/machine gun compression spring 5113. The sear crosspin 5112 and 8000 (Figure 16A) can be made in any desired caliber. the hammer link crosspin 5111 can secure the drop-in For example, the machine gun 100, as well as the semi- trigger block assembly 400 within the receiver assembly

10 19 EP 2 663 826 B1 20

102. trigger spring 7109, an open bolt arm spring bushing [0057] Figures 5C-5H are various elevational views of 7110, a socket head cap screw 7111, a socket head cap receiver assembly 102 of the machine gun 100 of Figure screw 7112, a closed bolt catch trigger spring bar 7113, 1, according to an embodiment. Figure 5C shows the a trigger bar spring plate 7114, an open bolt arm spring right side of the receiver assembly 102. Figure 5D shows 5 pin 7115, a safety cylinder 7116, a safety cylinder detent the rear of the receiver assembly 102. Figure 5E shows 7117, an open bolt arm safety lever 7118, an open bolt the bottom of the receiver assembly 102. Figure 5F lever safety spring 7119, a socket head cap screw 7120, shows the left side of the receiver assembly 102. Figure a selector detent pin 7121, a safety cylinder detent spring 5G shows the front of the receiver assembly 102. Figure 7122, an open bolt arm disconnector spring 7123, an 5H shows the top of the receiver assembly 102. 10 open bolt release lever spring 7124, a torsion damper [0058] Figures 5I-5L show the receiver assembly 102, spring retainer 7125, a spring plate cap 7126, a selection according to an embodiment. The trigger block assembly detent 7127, a selection detent spring 7128, an open bolt 400 is shown installed (dropped into) the receiver assem- full auto semi-auto selector cam 7129, a trigger block bly 102. gate 7130, a roll pin 7131, a trigger lock out spring 7132, [0059] Figures 6A and 6B are perspective views of the 15 a trigger block pin retension spring 7133, and an open receiver assembly 102 of the machine gun 100, accord- bolt full auto selector cam 7134. ing to an embodiment. The receiver assembly 102 has [0063] Figure 8 is a perspective view of a trigger lock- anopen bolt lower receiver 6101, a magazine catch 6102, out mechanism 800 of the machine gun 100, according a bolt catch 6103, a magazine catch button 6104, a bolt to an embodiment The trigger lock-out mechanism 800 catch release button 6105, a bolt catch release plunger 20 is shown with a trigger 801 locked out or blocked by a 6106, a hand grip 6107, a trigger guard 6108, a lock wash- trigger lock bar 802. When a dust cover 803 is open be- er 6109, a compression spring 6110, a wire spring 6111, cause the charging handle 109 is being pulled back, then a wire spring 6112, an upper retension pin 6113, an upper an arm 804 formed on the dust cover 803 partly rotates retension pin stock 6114, a lower retension pin 61, a re- triggerlock lever 833 which prevents rearward movement tension pin cap 6115, a retension pin cap 6116, a roll pin 25 of the trigger lock bar 802, which in turn prevent rearward 6117, an open bolt arm torsion damper assembly 6118, movement of the trigger 801. Thus, the trigger 801 cannot a receiver latch pin 6119, a receiver latch retension pin be pulled and the machine gun 100 cannot be fired when 6120, a receiver latch pin detent 6121, a receive latch the charging handle 109 is being pulled rearward, e.g., compression spring 6122, a dust cover assembly 6123, when the machine gun 100 is being cocked. The dust a dust cover hinge pin 6124, a dust cover spring 6125, 30 cover 803 can open approximately 7° to allow the charg- a slotted roll pin 6126, an ejector port cover lug 6127, an ing handle 109 to be pulled rearward to cock the machine ejector port cover assembly 6128, an ejector port cover gun 100, for example. hinge pin 6129, an ejection port cover torsion spring [0064] Figure 9 is a perspective view of a trigger lock- 6130, a slotted roll pin 6131, a low height rivet 6132, a out mechanism of the machine gun 100 showing the trig- handgrip bolt 6133, a torsion damper retainer 6134, a 35 ger 801 not locked out, according to an embodiment. trigger lock bar plunger 6135, a trigger lock bar 6136, a When the dust cover 803 is closed because the charging roll pin 6137, a trigger lock compression spring 6138, and handle 109 is not being pulled back and is in a forward a magazine catch spring 6139. position thereof, then the arm 804 formed on the dust [0060] Figures 6C-6H are various elevational views of cover 803 does not rotate trigger lever 833 to prevent receiver assembly 102 of the machine gun 100, accord- 40 rearward movement of the trigger lock bar 802 and there- ing to an embodiment. Figure 6C shows the right side of fore the trigger lock bar 802 does not prevent rearward the receiver assembly 102. Figure 6D shows the rear of movement of the trigger 801. Thus, the trigger 801 can the receiver assembly 102. Figure 6E shows the bottom be pulled and the machine gun 100 can be fired. of the receiver assembly 102. Figure 6F shows the left [0065] Figures 10A-10F are various elevational views side of the receiver assembly 102. Figure 6G shows the 45 of a semi-auto rifle 1000, according to an embodiment. front of the receiver assembly 102. Figure 6H shows the The semi-auto rifle 1000 is not capable of full auto fire. top of the receiver assembly 102. The semi-auto rifle 1000 can be fired from either an open [0061] Figures 6I-6L show the receiver assembly 102, bolt or a closed bolt, as selected by a user. Many of the according to an embodiment. The trigger block assembly features of the semi-auto rifle 1000 are substantially the 400 is removed from the receiver 102. 50 same as those of the machine gun 100 discussed above. [0062] Figures 7A-7G show the trigger block assembly For example, the barrel 105 can be released from the 400 of the machine gun 100, according to an embodi- semi-auto rifle 1000 in the same manner as for the ma- ment. The trigger block assembly 400 has an open bolt chine gun 100. Other features of the semi-auto rifle 1000 lever trigger pin 7101, an open bolt/closed bolt-full au- are different with respect to those of the machine gun to/semi auto open bolt-full auto/semi auto open bolt arm 55 100. For example, the machine gun 100 slam fires, can release lever 7102, a trigger 7103, a trigger block 7104, have a shorter barrel 105, and can have a heavy duty a trigger bar 7105, a disconnect 7106, a closed bolt catch stock 114, while the semi-auto rifle 1000 uses a hammer trigger bar pin 7107, an open bolt arm spring 7108, a 8203 (Figure 21B) to fire, can have a longer barrel 1005,

11 21 EP 2 663 826 B1 22 and can have a light weight collapsible stock 1014. Some autosear trip plunger 12123, a lock washer 12124, an of these different features are interchangeable between autosear trip plunger guide spring 12125, a latch receiver the semi-auto rifle 1000 and the machine gun 100. For retension pin 12126, an autosear trip plunger retainer example, either stock 114, 1001 and either barrel 105, screw 12127,a receiver latch pin detent12128, a receiver 1005 can be used on the semi-auto rifle 1000 and the 5 latch pin 12129, a roll pin 12130, a spring 12131, a spring machine gun 100. 13132, a roll pin 12133, a receiver latch compression [0066] Figures 10G-10I show a drop-in trigger assem- spring 12134, an open bolt arm torsion damper assembly bly 4000, according to an embodiment. The drop-in trig- 12135, a torsion damper retainer 12136, an SHCS ger assembly 4000 can be assembly outside of the semi- 12137, an autosear trip lever 12138, a trigger lock bar auto rifle 1000. Once assembled, the drop-in trigger as- 10 12139, a trigger lock bar plunger 12140, a trigger lock sembly 4000 can be dropped into place in the receiver compression spring 12141, and a magazine catch spring assembly 102, as discussed herein. Figures 11A and 11B 12142. show the drop-in trigger block assembly 4000 exploded [0070] Figures 12C-12H are various elevational views from the receiver assembly 102, according to an embod- of receiver assembly 102 of the semi-auto rifle 1000, ac- iment. The receiver assembly 102 has an 15 opencording to an embodiment. Figure 12C shows the right bolt/closed bolt semi auto lower receiver sub assembly side of the receiver assembly 102. Figure 12D shows the 11101, a hammer link crosspin 11102, an openrear of the receiver assembly 102. Figure 12E shows the bolt/closed bolt semi auto lower receiver sub assembly bottom of the receiver assembly 102. Figure 12F shows 11101, a hammer link crosspin 11102, an open bolt arm the left side of the receiver assembly 102. Figure 12G 11103, an open bolt arm sear 11104, a hammer shaft 20 shows the front of the receiver assembly 102. Figure 12H assembly 11105, a hammer link assembly 11106, a ham- shows the top of the receiver assembly 102. mer assembly 11107, a hammer shaft crosspin 11108, [0071] Figures 12I-12L show the receiver assembly a sear crosspin 11109, a safety lever 11110, an SHCS 102, according to an embodiment. The trigger block as- 11111, an autosear trip lever 11112, an open bolt arm sembly 4002 is removed from the receiver 102. pin 11113, an open bolt/closed bolt semi auto trigger25 [0072] Figures 13A-13H show the trigger block assem- block assembly 11114, a selector lever 11115, a closed bly 400 of the semi-auto rifle 1000, according to an em- bolt safety button assembly 11116, a take down lever bodiment. The trigger block assembly 400 has an open 11117, a selector cam assembly compression spring bolt lever trigger pin 13101, an open bolt arm open 11118, and a hammer mainspring 11119. bolt/closed bolt semi auto release lever 13102, open bolt [0067] Figures 11C-11H are various elevational views 30 full auto/semi auto open bolt/closed bolt semi auto trigger of receiver assembly 102 of the semi-auto rifle 1000, ac- 13103, auto sear 13104, a closed bolt disconnector cording to an embodiment. Figure 11C shows the right 13105, an open bolt/closed bolt trigger semi auto trigger side of the receiver assembly 102. Figure 11D shows the block 13106, an open bolt trigger bar 13107, an open rear of the receiver assembly 102. Figure 11E shows the bolt arm open bolt/closed bolt full auto/semi auto open bottom of the receiver assembly 102. Figure 11F shows 35 bolt full auto semi auto open bolt closed bolt semi auto the left side of the receiver assembly 102. Figure 11G disconnect 13108, a closed bolt sear 13109, an open bolt shows the front of the receiver assembly 102. Figure 11H catch trigger pin 13110, an open bolt and auto sear bush- shows the top of the receiver assembly 102. ing 13111, an open bolt closed bolt catch 13112, a trigger [0068] Figures 11I-11J show the receiver assembly spring 13113, an open bolt arm spring bushing 13114, 102, according to an embodiment. The trigger block as- 40 an SHCS 13115, an SHCS 13116, a closed bolt catch sembly 400 is shown installed (dropped into) the receiver trigger bar spring 13117, a trigger bar plate spring 13118, assembly 102. an open bolt arm spring pin 13119, a closed bolt sear [0069] Figures 12A and 12B are perspective views of spring plunger 13120, a safety cylinder 13121, a safety the receiver assembly 102 of the machine gun 100, ac- cylinder detent 13122, a closed bolt selector safety pawl cording to an embodiment. The receiver assembly 102 45 13123, an open bolt arm safety lever 13124, a closed has an open bolt/closed bolt semi auto lower receiver bolt lever safety spring 13125, a SHCS 13126, a selector 12101, a magazine catch 12102, a bolt catch 12103, a detent pin 13127, a safety cylinder detent spring 13128, magazine catch button 12104, a bolt catch release button a closed bolt sear spring 13129, a closed bolt selector 12105, a bolt catch release plunger 12106, a dust cover safety pawl spring 13130, a closed bolt arm disconnector hinge pin 12107, a slotted roll pin 12108, a spring dust 50 spring 13131, an open bolt release lever spring 13132, cover 12109, an eject port cover hinge pin 12110, an a torsion damper spring retainer 13133, a spring plate eject port cover 12111, a slotted roll pin 12112, a low cap 13134, a selector detent 13135, a selector detent height rivet 12113, an eject port cover assembly 12114, spring 13136, an autosear trip lever assembly 13137, an an ejection port cover torsion spring 12115, a hand grip autosear trip lever support 13138, a closed bolt discon- 12116, a dust cover assembly 12117, a trigger guard 55 nector autosear spring 13139, a trigger block gate 13140, 12118, an backbone stock retension pin LH 12119, an a roll pin 13141, a trigger lock out spring 13142, a receiver backbone stock retension pin RH 12120, a lower receiver latch retension pin 13143, an open bolt/closed bolt semi stock retension pin 12121, a retention pin cap 12122, an auto selector cam 13144, a trigger block retension spring

12 23 EP 2 663 826 B1 24 pin 13145, and an open bolt arm spring 13146. barrel latch 113 on the backbone 103, as discussed here- [0073] Figures 14A-14F are additional views of the in. The barrel assembly 104 can have a fore grip 106. semi-auto rifle 1000, according to an embodiment. The [0082] A stock 114 can be removably attachable to the semi-auto rifle 1000 can have the lower receiver or re- receiver assembly 102. The stock 114 can be pivotally ceiver assembly 102. The receiver assembly 102 can 5 attached to the receiver assembly 102 such that the stock include a grip 107 and a magazine well 108. 114 can fold to either side of the receiver assembly 102. [0074] The backbone 103 constrains a bolt carrier 111, The stock 114 can be a heavy duty stock, as shown. as described herein. A charging handle 109 can be slid- Alternatively, the stock 114 can be a lightweight stock or ably disposed between the backbone 103 and the receiv- any other type of stock. er assembly 102 so as to facilitate cocking of the machine 10 [0083] Figures 16G-16I show a drop-in trigger block gun 100 by pulling a bolt carrier 111 rearward. A spring assembly 8003, according to an embodiment. The trigger guide 112 can be at least partially disposed within the block assembly 8003 can be assembled outside of the bolt carrier 111 and can define an anti-bounce system, rifle/machine gun 8000. Once assembled, the trigger as discussed herein. block assembly 400 can be dropped into place in the [0075] A barrel assembly 104 can be removably de- 15 receiver assembly 102, as discussed herein. tachable from the semi-auto rifle 1000 by pressing a bar- [0084] Figures 17A and 17B show the trigger block as- rel latch 113 on the backbone 103, as discussed herein. sembly 8003 exploded from the receiver assembly 102, The barrel 105 can have a fore grip 106. The barrel 105 according to an embodiment. The sear crosspin 1709 can be shorter that that shown in Figures 10A-10F for and the hammer link crosspin 1702 can secure the drop- the semi-auto rifle 1000. 20 in trigger block assembly 400 within the receiver assem- [0076] A stock 114 can be removably attachable to the bly 102. Two hook pivots 1791 can be formed on the front receiver assembly 102. The stock 114 can be pivotally of the receiver assembly 102 to facilitate partial separa- attached to the receiver assembly 102 such that the stock tion of the receiver assembly 102 from the backbone 103. 114 can fold to either side of the receiver assembly 102. The hook pivots 1791 can hook around and pivot about The stock 114 can be a heavy duty stock, as shown.25 backbone studs 198 (Figure 4A). The lower receiver or Alternatively, the stock 114 can be a lightweight stock receiver assembly 102 can pivot downwardly approxi- such as that shown in Figures 10A-10F or can be any mately 40° from two backbone studs 198 while remaining other type of stock. pivotally attached to the backbone 103. The receiver as- [0077] Figures 14G-15C show a drop-in trigger assem- sembly 102 can be detached from the backbone or back- bly 4000, according to an embodiment. The drop-in trig- 30 bone 103 when the receiver assembly 102 is pivoted ger assembly 4000 can be assembly outside of the semi- down approximately 20° or halfway where a gap in the auto rifle 1000. Once assembled outside of the receiver hook pivot 1791 allows the receiver assembly 102 to be assembly 102, the drop-in trigger assembly 4000 can be lifted up and off the backbone studs 198. Alternatively, dropped into place in the receiver assembly 102, as dis- thereceiver assembly102 can use straight slots 119 (Fig- cussed herein. 35 ure 4A). [0078] Figure 16A shows of rifle/machine gun 8000, [0085] The receiver assembly 102 can have an open according to an embodiment. The rifle/machine gun 8000 bolt/closed bolt full auto/semi auto lower receiver sub- is capable of semi-auto and full auto fire, as selected by assembly 17101, a hammer link crosspin 17102, an open the user. The rifle/machine gun 8000 can be fired from bolt arm 17103, an open bolt arm sear 17104, a hammer either an open bolt or a closed bolt, as selected by a user. 40 shaft assembly 17105, a hammer link assembly 17106, Many of the features of the semi-auto rifle 1000 are sub- a hammer assembly 17107, a hammer shaft crosspin stantially the same as those of the machine gun 100 dis- 17108, a sear crosspin 17109, a safety lever 17110, an cussed above. SHCS 17111, an autosear trip lever 17112, an open bolt [0079] Figures 16B-16F are additional views of the ri- arm pin 17113, an open bolt/closed bolt-full auto/semi fle/machine gun 8000, according to an embodiment. The 45 auto trigger block assembly 17114, a selector lever rifle/machine gun 8000 has a lower receiver or receiver 17115, a closed bolt safety button assembly 17116, a assembly 102. The receiver assembly 102 can include takedown lever 17117, a selector cam assembly com- a grip 107 and a magazine well 108. pression spring 17118, a selector cam assembly com- [0080] The backbone 103 constrains a bolt carrier 111, pression spring17118, and a hammer mainspring17119. as described herein. A charging handle 109 can be slid- 50 [0086] Figures 17C-17H are various elevational views ably disposed between the backbone 103 and the receiv- of receiver assembly 102 of the rifle/machine gun 8000, er assembly 102 so as to facilitate cocking of the rifle/ma- according to an embodiment. Figure 17C shows the right chine gun 8000 by pulling a bolt carrier 111 rearward. A side of the receiver assembly 102. Figure 17D shows the spring guide 112 can be at least partially disposed within rear of the receiver assembly 102. Figure 17E shows the the bolt carrier 111 and can define an anti-bounce sys- 55 bottom of the receiver assembly 102. Figure 17F shows tem, as discussed herein. the left side of the receiver assembly 102. Figure 17G [0081] A barrel assembly 104 can be removably de- shows the front of the receiver assembly 102. Figure 17H tachable from the rifle/machine gun 8000 by pressing a shows the top of the receiver assembly 102.

13 25 EP 2 663 826 B1 26

[0087] Figures 17I-17L show the receiver assembly catch trigger bar pin 19110, a closed bolt and auto sear 102, according to an embodiment. The trigger block as- bushing 19111, an open bolt arm open bolt catch 19112, sembly 8003 is shown installed (dropped into) the receiv- a trigger spring 19113, an open bolt arm spring bushing er assembly 102. 19114, an SHCS 19115, an SHCS 19116, a closed bolt [0088] Figures 18A and 18B are perspective views of 5 catch trigger bar spring 19117, a trigger bar spring plate the receiver assembly 102 of the rifle/machine gun 8000, 19118, an open bolt arm spring pin 19119, a closed bolt according to an embodiment. The receiver assembly 102 sear spring plunger 19120, a safety cylinder 19121, a has an open bolt/closed bolt full auto/semi auto lower safety cylinder detent 19122, a closed bolt selector safety receiver 18101, a magazine catch 18102, a bolt catch pawl 19123, an open bolt arm lever safety 19124, an 18103, a magazine catch button 18104, a bolt catch re- 10 open bolt lever safety spring 19125, an SHCS 19126, a lease button 18105, a bolt catch release plunger 18106, selector detent pin 19129, a safety cylinder detent spring a dust cover hinge pin 18107, a slotted roll pin 18108, a 19128, a closed bolt sear spring 19129, a closed bolt dust cover spring pin 18109, an eject port cover hinge selector safety pawl spring 19130, a closed bolt arm dis- pin 18110, an eject port cover lug 18111, a slotted roll connectorspring 19131, an openbolt release lever spring pin 18112, a low height rivet 18113, an eject port cover 15 19132, a torsion damper retainer spring 19133, a spring assembly 18114, an ejection port cover torsion spring plate cap 19134, a selector detent 19135, a selector de- 18115, a hand grip 18116, a dust cover assembly 18117, tent spring 19136, an autosear trip lever assembly 19137, a trigger guard 18118, an LH backbone retension stock an autosear trip lever support 19138, a closed bolt dis- pin 18119, an RH backbone retension stock pin 18120, connector autosear spring 19139, a trigger block gate a lower receiver retension stock pin 18121, a retension 20 19140, a roll pin 19141, a trigger lock out spring 19142, pin cap 18122, an autosear trip plunger 18123, a lock an open bolt/closed bolt full auto semi auto selector cam washer 18124, an autosear trip plunger guide spring 19144, a trigger block retension spring pin 19145, and 18125, a receiver latch retention pin 18126, an autosear an open bolt arm spring 19146. trip plunger retainer screw 18127, a receiver latchpin de- [0092] Figures 20-21B show components of the ri- tent 18128, a receiver latchpin 18129, a roll pin 18130, 25 fle/machine gun 8000 in a closed bolt firing configuration, a spring 18131, a spring 18132, a roll pin 18133, a re- according to an embodiment. The rifle/machine gun 8000 ceiver latch compression spring 18134, an open bolt arm has an autosear trip bar 8012, an autosear trip plunger torsion damper assembly 18135, a torsion damper re- 8201, an open bolt sear 8202, a hammer 8203, an open tainer 18136, an SHCS 18137, an autosear trip lever bolt arm 8204, a closed bolt open bolt arm catch 8205, 18138, a trigger lock bar 18139, a trigger lock bar plunger 30 an autosear reversing lever 8206, an autosear trip lever 18140, a trigger lock compression spring 18141, and a 8207, a closed bolt sear 8015, a hammer link 8014, a magazine catch spring 18142. trigger lock bar 8208, a closed bolt disconnector 8209, a [0089] Figures 18C-18H are various elevational views trigger 8210, an open bolt arm release lever safety lock of receiver assembly 102 of the rifle/machine gun 8000, 8211, an open bolt disconnector 8212, an open bolt re- according to an embodiment. Figure 18C shows the right 35 lease lever 8213, and a bolt carrier 111. side of the receiver assembly 102. Figure 18D shows the [0093] The bolt 8011 is closed and locked. The auto- rear of the receiver assembly 102. Figure 18E shows the sear trip bar 8012 is pulled forward by the bolt carrier 111 bottom of the receiver assembly 102. Figure 18F shows and an autosear 8013 (see Figure 26) has been tripped. the left side of the receiver assembly 102. Figure 18G A hammer link 8014 is release by a closed bolt sear 8015. shows the front of the receiver assembly 102. Figure 18H 40 The trigger charge handle lock-out mechanism 800 (see shows the top of the receiver assembly 102. Figure 8) is disengaged. The open bolt arm catch 8205 [0090] Figures 18I-18L show the receiver assembly is deployed and the open bolt arm 8204 is caught in a 102, according to an embodiment. The trigger block as- downward location. The trigger 8210 is pulled and the sembly 8003 is removed from the receiver 102. hammer 8203 is release so that the rifle/machine gun [0091] Figures 19A-19I show the trigger block assem- 45 8000 fires. bly 8003 of the rifle/machine gun 8000, according to an [0094] With particular reference to Figure 21A, the embodiment. The trigger block assembly 400 has 19A - hammer link 8014 has been released by the close bolt an open bolt lever trigger pin 19101, an open bolt arm sear hook 8235 allowing the hammer link 8014 to move. open bolt/closed bolt-full auto/semi auto, open bolt-full With particular reference to Figure 21B, a tip of the close auto/semi auto release lever 19102, an open bolt full au- 50 bolt open bolt arm catch 8205 captures the open bolt arm to/semi auto open bolt/closed bolt full auto semi auto notch 8220. open bolt/closed bolt semi auto trigger 19103, an auto [0095] A firing pin retaining pin 8043 maintains the fir- sear 19104, a closed bolt disconnector 19105, an open ing pin 8044 within the bolt 8011 and the bolt carrier 111. bolt/closed bolt full auto/semi auto trigger block 19106, The firing pin retaining pin 8043 can also transfer forward an open bolt trigger bar 19107, an open bolt arm open 55 movement of the bolt carrier to firing pin 8044 to fire the bolt/closed bolt full auto auto/semi auto open bolt closed machine gun 8000 such as during slam firing thereof. full auto semi auto open bolt/closed bolt semi auto dis- [0096] Figures 22-23B shows components of the ri- connect 19108, a closed bolt sear 19109, a closed bolt fle/machine gun 8000 in a closed bolt firing configuration,

14 27 EP 2 663 826 B1 28 according to an embodiment The bolt 8011 is closed and the receiver latch pin 8241, when rotated to open the locked. The autosear trip bar 8012 is pulled forward by rifle/machine gun 8000, will bear against the autosear the bolt carrier 111. The autosear 8013 is tripped. The trip bar to prevent further rotation of the receiver latch pin hammer link 8014 has been released by the closed bolt 8241. In this manner, the rifle/machine gun 8000 is pre- sear 8015. The trigger charge handle lock-out mecha- 5 vented from be opened until the bolt carrier 111 is posi- nism 800 (see Figure 8) is disengaged. The open bolt tioned forward so as to release compression of the drive arm catch 8205 is deployed and the open bolt arm 8204 spring 8355 (Figure 38B). Thus, the rifle/machine gun is caught in a downward location. The trigger 8210 is 8000 cannot be opened when the drive spring 8355 is pulled. compressed, which would be unsafe. [0097] With particular reference to Figure 23A, the10 [0104] Figures 33A-33L are various views showing a hammer link 8014 has released the close bolt sear hook selector cam layout according to an embodiment. Figure 8235 allowing the hammer link 8014 to move. With par- 33A shows the selector 2051 as viewed looking forward ticular reference to Figure 21B, a tip of the close bolt open at the selector 2051. Figure 33B shows the selector 2051 bolt arm catch 8205 captures the open bolt arm notch in a closed bolt, semi auto position. Figure 33C shows 8220. 15 the selector 2051 as viewed looking rearward at the se- [0098] Figures 24-25B shows components of the ri- lector 2051. Figures 33D-33L show the cross-sections fle/machine gun 8000 in a closed bolt firing configuration, of the selector 2051 taken through lines 33D-33L of Fig- according to an embodiment. The bolt 8011 is closed and ure 33A. locked. The autosear trip bar 8012 is pulled forward by [0105] Figures 34A-34D are various views showing in- the bolt carrier 111. The autosear 8013 is tripped. The 20 stallation of the barrel 105, according to an embodiment. hammer link 8014 is held by the closed bolt sear 8015. Figure 34A shows the barrel 105, ramp 8252, and back- The trigger charge handle lock-out mechanism 800 (see bone 103 in an exploded view. Figure 34B shows the Figure 8) is disengaged. The open bolt arm catch 8205 ramp 8252 attached to the backbone 103. The barrel 105 is deployed and the trigger 8210 is not pulled. is positioned such that the barrel 105 can be pushed rear- [0099] With particular reference to figure 25A, the ham- 25 ward to facilitate attachment to the backbone 103. Figure mer link 8014 is held by the closed bolt sear hook 8235. 34C shows the barrel 105 pushed rearward such that the [0100] Figures 26-27B show the open bolt firing mech- pin 8254 contacts the swinging wedge 8253 attached to anism of the rifle/machine gun 8000 in a fired condition the barrel latch 113. Figure 34D shows the pin 8254 cap- with the bolt 8011 locked and the autosear 8013 tripped, tured by the swinging wedge 8253. The swinging wedge according to an embodiment. The autosear trip bar 8012 30 8253 holds the pin 8254, can consequently the barrel is pulled forward by the bolt carrier 111. The open bolt 105, to the backbone 103. arm 8202 is moved down by spring pressure from the [0106] Figures 34E-34G are various views showing re- bolt carrier 111 and is held down until the trigger 8210 is moval of the barrel 105, according to an embodiment. released. The hammer 8203 is allowed to move forward Figure 34E shows the barrel 105, ramp 8252, and back- by the hammer link 8014. The autosear trip plunger 8201 35 bone 103 in an exploded view. Figure 34F shows the is cammed downward by the autosear trip bar 8012. The barrel 105 attached to the backbone 103. When the barrel autosear trip lever 8207 and support 8213 are rotated by latch 113 is pushed downwardly, then the swinging the reversing lever 8206. The autosear 8013 is tripped wedge 8253 will swing to the left to release the pin 8254, by the trip lever 8207 releasing the hammer link hook thus allowing the barrel 105 to drop downwardly, as 8091. The open bolt release lever 8213 is pushed forward 40 shown by the arrow. Figure 34G shows that as the barrel by the trigger bar 8019 to release the open bolt arm 8202. 105 drops downwardly, the proximal end 8254 of the bar- [0101] Figures 28-29B show an open bolt firing mech- rel 105 is ramped forward by the cam 8262 by a distance anism of the rifle/machine gun 8000 in a firing condition approximately equal to one wall thickness of the barrel with the bolt 8011 unlocked, according to an embodi- 105. More particularly, a ramp cam 8262 of the ramp ment. The open bolt arm 8202 is moved down by spring 45 8252 can cam a corresponding barrel cam 8262 to effect pressure from the bolt carrier 111 and is held down until such ramping forward of the barrel 105. A second cam the trigger 8210 is released. The open bolt release lever 8259 (Figure 4A) can cam the barrel 105 forward further 8213 is pushed forward by the trigger bar 8019 to release such that the barrel 105 does not contact the magazine the open bolt arm 8202. 101 as the barrel 105 drop clear of the firearm. [0102] Figures 30-31B show an open bolt firing mech- 50 [0107] Figures 35A-35D are various views showing a anismof the rifle/machinegun 8000 in aseared condition, barrel 105 attached to a backbone 103, according to an according to an embodiment. In the seared condition, the embodiment. Figure 35A is a top view of the barrel 105 bolt carrier 111 is held rearward under spring tension by and the backbone 103. Figure 35B is a perspective view the open bolt sear 8202. showing the barrel 105 exploded away from the back- [0103] Figure 32 shows the autosear trip bar 8012 of 55 bone 103. Figure 35C is a side view showing the barrel the rifle/machine gun 8000, according to an embodiment. 105 attached to the backbone 103. Figure 35D is a cross- When the bolt 8011 is in a rearward position, then the sectional side view showing the barrel 105 attached to autosear trip bar 8012 is also to the rear. In this instance, the backbone 103.

15 29 EP 2 663 826 B1 30

[0108] Figures 36A-36G are various views showing a 8253, according to an embodiment. A cam pin 8071 ex- barrel latch 113, according to an embodiment. The barrel tends from the bolt 8011 into a slot 8072 formed in the latch 113 attaches the barrel 105 to the backbone 103 backbone 103. The slot 8072 cooperates with the cam and facilitates removal of the barrel 105 from the back- pin 8071 to prevent the bolt 8011 from rotating when the bone 103. The barrel latch 113 includes a pivot hole 8255 5 cam pin 8071 is in the slot 8072. and the swinging wedge 8253. Thus, the barrel latch 113 [0116] The bolt carrier has an upper portion 8073, a andthe swinging wedged 8253can be formed as a single, lower portion 8074, and a waist interconnecting the upper monolithic unit. Alternatively, the barrel latch 113 and the portion 8073 and the lower portion 8074. The waist 8075 swinging wedge 8253 can be formed as two or more sep- is slidably disposed within the slot 8072. arate pieces. 10 [0117] Figures 51A-51F are various views showing a [0109] Figure 37 is a drawing that shows how the curve bolt8011 aligned with a barrel 105 with the backbone 103 is defined for the swinging wedge 8253, according to an locked to the barrel 105 via the swinging wedge 8253, embodiment. The swinging wedge 8253 engages and according to an embodiment. The slot 8072 can have a captures the pin 8254 attached to the barrel 105 to attach cutout 8076 formed therein. The cam pin 8071 can enter the barrel 105 to the backbone 103. A pivot 8300 of the 15 the cutout 8076 from the slot 8072 to allow rotation of the swinging wedge 8253 is offset with respect to a radius bolt 8011 and thereby allow the bolt 8011 to lock to the of the swinging wedge 8253. Thus, the pivot 8300 and barrel extension 8606. the center 8301 of the radius are not concentric with re- [0118] Figures 52A-52C show the backbone 103 and spect to one another. A line from the pivot 8300 to a given the barrel 105 with various cross-sections, according to point on the curve can form an angle of approximately 20 an embodiment. The pin 8254 can be attached to the 8° with respect to a radius of the curve. barrel 105 via a strap. [0110] Figures 38A-48 are various views showing a [0119] Figures 53A-53C show the backbone 103 and spring assembly 8350, according to an embodiment. The the barrel 105 with various cross-sections, according to spring assembly 8350 can function both as a spring guide an embodiment. The swinging wedge 8253 can pull the for the drive spring and as an anti-bounce system, as 25 barrel 105 up into two V-bocks 8081 and 8082. The use discussed herein. The spring assembly 8350 has a tube of V-blocks 8081 and 8082 assures proper alignment of assembly 8351, a spring guide 8352, a spring keeper the barrel 105 with respect to the backbone 103. A groove 8353,an anti-bounce springkeeper 8354, a recoilor drive 8086 can be formed in the rear v-block to receive a flange spring 8355, and an anti-bounce spring 8356. The spring 8087 of the barrel extension 8088. guide 8352 moves within the tube assembly 8351 to de- 30 [0120] Figures 54A-54D show the backbone 103 and fine a weight that mitigates bouncing of the bolt carrier the barrel 105 with various cross-sections, according to 111. an embodiment. The barrel 105 is shown detached from [0111] With particular reference to Figure 41, a spring the backbone 103. The strap 8080 can be replaced or guide insert 8360 blocks the anti-bounce weight from be- configured, e.g., bent or shaped, so as to define a ten- ing pushed out of the spring guide 8352 during normal 35 sioner 8083. The tensioner 8083 can provide a desired disassembly of the firearm. preload. For example, the tensioner 8083 can provide a [0112] With particular reference to Figures 42A-42D, preload of approximately 317.52 kg (700 lbs). when the a spring guide cap keeps the drive spring 8355 on the barrel 105 is attached to the backbone 103 via the swing- spring guide 8352. With particular reference to Figures ing wedge 8253. 44A, the anti-bounce spring keeper 8353 keeps the anti- 40 [0121] Figures 55A-55D show the backbone and the bounce spring 8356 on the spring guide 8352. barrel with various cross-sections, according to an em- [0113] Figure 46 shows the anti-bounce system with bodiment. The barrel 105 is shown attached to the back- the drive spring 8355 compressed (top) and with the drive bone 103. The tensioner 8083 is applying the preload to spring extended (bottom), according to an embodiment. the barrel 105 to properly seat the barrel 105 within the Figure 47 showing the anti-bounce system with the 8455 45 V-blocks 8081 and 8082. spring compressed (top) and with the drive spring ex- [0122] Figures 56A-56D are various views showing re- tended (bottom), according to an embodiment. Figure 48 lease of the barrel 105, according to an embodiment. is an exploded perspective view of anti-bounce system, When the barrel latch 113 is pushed downwardly, the according to an embodiment. Timing for the anti-bounce swinging wedge 8253 disengages or releases the pin weight can be at least partially determined by a distance 50 8254 to allow the barrel 105 to fall free of the firearm, as between the front end of the anti-bounce weight and the discussed herein. inside of the front cap of the bolt carrier 8011. [0123] Figures 57A-57D are various views showing the [0114] Figure 49 is perspective view showing a back- gas system, according to an embodiment. Gas from a bone 103 and bolt carrier 111, according to an embodi- fired cartridge enters the gas system via barrel gas port ment. 55 7501. The gas flows from the barrel gas port 7501 to a [0115] Figures 50A-50G are various views showing a gas metering port 7502 with the gas block 7503. The gas bolt 8011 aligned with a barrel 105 with the backbone metering port 7502 determines, at least in part, the 103 not locked to the barrel 105 via the swinging wedge amount and pressure of gas provided to the gas system.

16 31 EP 2 663 826 B1 32

The gas port is discussed in further detail with reference [0130] Surfaces of the generally tubular portion of the to Figures 72-74 below. bolt carrier can bear against or contact the inner wall of [0124] Gas piston rings 7001 can provide an enhanced the backbone to control the motion of the bolt carrier. For seal, as discussed herein. The gas piston rings 7001 can example, the bolt carrier can have surfaces of contact be disposed upon a piston 7003, which can be disposed 5 with backbone that are forward and aft on bolt carrier. within a cylinder 7004. The gas piston 7003 can drive the These contact surfaces of the bolt carrier can slide within bolt carrier 111 to operate the firearm. More particularly, the backbone and can facilitate guiding of the bolt carrier, the gas piston 7003 can abut a protrusion 7506 formed at least to some degree. upon a forward end of the bolt carrier 111 to push the [0131] The bolt carrier can have four surfaces 151 (fig- bolt carrier 111 rearward when the firearm discharges. 10 ure 4A) that contact backbone that are forward on the Protrusions 121 can be formed upon the piston 7003 and bolt carrier and can have four surfaces 152 (figure 4A) can slide within guide slots 122 (Figure 14A) to define that contact the backbone that are aft on bolt carrier. The the motion of the piston 7003. A flash guard 123 (Figure bolt carrier can have three surfaces of contact with back- 14A) can obscure, hide, or diffuse flash exhausting from bone that are forward on the bolt carrier and can have the guide slots 122 when the firearm is discharged. 15 three surfaces of contact with the backbone that are aft [0125] Overheating of the barrel of a firearm can be on bolt carrier. The bolt carrier can any desired number mitigated by more readily facilitating barrel changes. surfaces of contact with backbone that are forward and Changing the barrel of a contemporary firearm, such as any desired number surfaces that are aft on bolt carrier. the M16 or M4, during a firefight is generally not practical. The number of forward surfaces of contact do not have According to an embodiment, the barrel of a firearm can 20 to equal the number of aft surfaces of contact. bechanged quickly, even under adverseconditions, such [0132] By providing surfaces of contact that are for- as during a firefight. Thus, a soldier can have several, ward and aft on the bolt carrier, the configuration and e.g., four or five, barrels on hand and can change barrels dimensions of the bolt carrier at other portions thereof each time that a barrel get too hot, such as after a pre- can be less critical. For example, the diameter of the bolt determined number of shots are fired or a predetermined 25 carrier can vary substantially between the forward and number of magazines are used. The barrels can be re- aft contact surfaces without adversely affecting the op- used afterthey have cooled. Thus, a soldier cangenerally eration of the firearm. By providing surfaces of contact continue to shoot until the ammunition supply is exhaust- that are forward and aft on the bolt carrier, the stability ed. of the bolt carrier with respect to the backbone is en- [0126] According to an embodiment, the ability to30 hanced. quickly change the barrel is facilitated by the use of a [0133] According to an embodiment, part of the bolt backbone and bolt carrier structure, as discussed herein. carrier can be within backbone and part out the bolt car- According to an embodiment, the ability to quickly change rier can be outside of the backbone. The part of the bolt the barrel is further facilitated by the use of a swinging carrier that is outside of the backbone can be below the wedge, tensioner, and other features, as discussed here- 35 backbone. Thus, the bolt carrier can comprise an upper in. The use of a backbone allows the bolt carrier to be portion (inside the backbone) and a lower portion (below moved out of the receiver, at least to some degree. the backbone). The upper portion can be substantially [0127] According to an embodiment, a backbone re- longer that the lower portion. The upper portion can ex- places the backbone of a contemporary firearm. The tend substantially forward of the when the bolt backbone can comprise a tube having a generally round 40 is locked, such that a telescoping bolt carrier is defined. cross-section. The backbone can comprise a tube having The lower portion can include the bolt. a generally rectangular, e.g. square, cross-section. The [0134] The backbone can have a slot form therein to backbone can comprise a tube having any desired cross- facilitate connection of the upper portion of the backbone section or combination of cross-sections. to the lower portion of the backbone. The upper portion [0128] The backbone can guide the bolt carrier. A por- 45 of the backbone can be connected to the lower portion tion of the bolt carrier can move within the backbone. of the backbone at a waist of the bolt carrier. The waist That portion of the bolt carrier that moves within the back- can be a portion of reduced cross-sectional width of the bone can be attached to another portion of the bolt carrier bolt carrier. The waist of the bolt carrier can slide within that contains the bolt. A portion of the bolt carrier can the slot of the backbone. The width of the slot is such move outside of the backbone. That portion of the bolt 50 that excessive lateral movement of the lower portion of carrier that moves outside of the backbone can contain the bolt carrier is inhibited. Thus, the slot of the backbone the bolt. can guide the bolt carrier in the fore and aft movement [0129] For example, the bolt carrier can comprise an of the bolt carrier as the firearm cycles. elongated generally tubular portion 150 (Figure 4A) that [0135] Movement of the bolt carrier is not motion con- slides within the backbone. A portion of the bolt carrier 55 strained by a receiver, as is common in contemporary can be formed from tube stock. For example, that portion firearms. Rather, movement of the bolt carrier can be of the bolt carrier that moves within the backbone can be motion constrained by the backbone. formed from tube stock. [0136] A lug lock can have a twist tab or cam pin that

17 33 EP 2 663 826 B1 34 travels within the slot and that exits the slot (such as to the tensioner via the pin. one side thereof) as the lugs of the bolt reach their for- [0143] That is, the radius that defines the surface of wardmost position so as to effect rotation of the bolt to the swinging wedge can be taken from a point that is engage the lugs and lock the bolt in a firing position. A offset with respect to the pivot point of the swinging release notch formed in slot (as an extension of the slot 5 wedge. As such, the surface of the swinging wedge can to one side thereof) can cause the cam pin to rotate when have a different radius as compared to the radius taken the cam pin is cammed by bolt carrier lower portion to from the pivot point of the swinging wedge, as shown in rotatelugs and lock bolt. The release notch can be formed Figure 37. and positioned so as to allow the cam pin to rotate after [0144] More particularly, the approximately 8 degree cam pin moves out of dwell. 10 angle can be present along the swinging wedge at each [0137] The use of such a backbone can facilitate the point on the swinging wedge where the pin can contact construction of a firearm having a quick barrel change the swinging wedge. That is, wherever the pin contacts feature wherein the barrel drops downwardly, under the the swinging wedge, the wedge is effectively at an 8 de- force of gravity, when the barrel is released from the fire- gree angle with respect to the force applied by the pin. arm, e.g., from the backbone of the firearm. A new barrel 15 Since this angle does not vary substantially along the can be rapidly snapped into place. Thus, the barrel can swinging wedge, it does not matter substantially where be quickly changed in battlefield conditions. along the swinging wedge the pin is positioned to attach [0138] According to an embodiment, a swinging wedge the barrel to the firearm. can be pivotally attached to the backbone. The swinging [0145] Regardless of where the pin is positioned along wedge can engage a pin attached to the barrel to hold 20 the swinging wedge, the force applied by the pin to the the barrel to the firearm. For example, the swinging swinging wedge is substantially the same and the force wedge can have two wedged paws and each wedged required to push the barrel latch down to release the bar- paw can engage one end of the pin. A single pin can be rel does not vary substantially. Because of the 8 degree engaged by the two wedged paws or two separate pins angle,expansion of thebarrel doesnot causethe position can be engaged by the paws. 25 of the pin upon the swinging wedge to change substan- [0139] A barrel latch can be formed with the swinging tially. Expansion of the barrel does not cause the pin to wedge such that actuating, e.g., depressing, the barrel slide along the wedge. latch causes the swinging wedge to rotate and release [0146] The swinging wedge can be defined by chan- the barrel from the firearm. When the swinging wedge nels formed within the paws that receive the ends of the rotates, it can slide against the tension caused by contact 30 pin. The channels can be curved to define the swinging with the pin. The swinging wedge can be spring biased wedge so as to pull the pin (and consequently the barrel) toward a position thereof that holds the barrel to the fire- closer to the backbone as the wedge slides into tighter arm. Thus, the barrel latch can be moved against spring contact with the pin. tension to release the barrel. [0147] According to an embodiment, a tensioner can [0140] The swinging wedge and the pin can be config- 35 apply a predetermined amount of tension to the pin when ured such that approximately the same force, e.g., ten- the pin engages the swinging wedge. The tension can sion, is applied by the swinging wedge to the pin any- hold the barrel to the firearm. For example, the tension where along the swinging wedge. The swinging wedge can hold the barrel against one or more v-blocks that are can provide approximately the same force regardless of formed to the backbone. The v-blocks can assure proper where along the swinging wedge the pin contacts the 40 alignment of the barrel with respect to the backbone. The swinging wedge. v-blocks are spaced sufficiently apart with respect to one [0141] The swinging wedge can be a curved swinging another so as to adequately stabilize the barrel with re- wedge. The pivot point and the curve of the swinging spect to the firearm. wedge can be non-concentric. The pivot point and the [0148] The tensioner can be defined by a spring that curve of the swinging wedge can be defined such that 45 at least partially surrounds the barrel. The tensioner can the swinging wedge provides approximately the same be disposed proximate where the swinging wedge is po- force regardless of where along the swinging wedge the sitioned on the firearm. The tensioner can be attached pin contacts the swinging wedge. to the pin, such that pulling the pin away from the barrel [0142] For example, the pivot point and the curve of stretches the tensioner and thus applies tension to the the swinging wedge can be configured such that at points 50 pin. Thus, as the swinging wedge pulls the pin away from of contact between the pin and the swinging wedge, a the barrel, the tensioner applies tension to the pin that tangent to any point on the curve of the swinging wedge tends to pull the pin toward the barrel. Further, as the is at an angle of approximately 8 degrees with respect barrel expands due to heating of the barrel during firing to a perpendicular to a line through that point and the and thus moves radially away from the backbone, addi- pivot point of the swinging wedge. This angle allows the 55 tional tension is accommodated by the tensioner. swinging wedge to readily slide during installation and [0149] The v-blocks cooperate with the tensioner, pin, removal of the barrel and also inhibits undesirable move- and swinging wedge to accommodate thermal expansion ment of the swinging wedge due to tension applied by of barrel while maintaining alignment. Thus, as the barrel

18 35 EP 2 663 826 B1 36 expands due to the heat during firing, desired alignment the barrel is moved forward substantially more. Two cam- of the barrel with respect to the backbone is maintained. ming surfaces are provided on the firearm, proximate the [0150] According to an embodiment, as barrel expands rear end of the barrel. These two camming surfaces se- longitudinally, it simply slides in v-blocks. As the barrel rially contact the rear end of the barrel as the barrel falls expands radially, the barrel does not push the swinging 5 from the firearm in a manner that pushes or cams the wedge backwards (towards the barrel release position barrel forward as the barrel falls. of the swinging wedge) against spring tension. The [0156] More particularly, a first camming surface can swinging wedge is not pushed backwards because of the be formed on the lower receiver to move the barrel slightly approximately 8 degree angle thereof. That is, the angle forward during barrel release and a second, larger cam- is not sufficient (steep enough) to allow the pin to move 10 ming surface can be formed on the backbone to move the swinging wedge. Rather, the angle is such that the the barrel more forward as the barrel drops further. The swinging wedge can move the pin, but not visa versa. As two stages of the camming process assure that the barrel barrel expands radially, the tensioner accommodates moves forward sufficiently so as to drop cleanly away this radial expansion. from the firearm. In particular, the barrel moves forward [0151] The tensioner can have a preload of approxi- 15 sufficiently so as to drop away from the firearm without mately 317.52 kg (700 lbs.), for example. This preload contacting the magazine as the barrel falls. This both can accommodate the heat expansion of the barrel that assuresthat the barrel properlydetaches fromthe firearm causes the barrel to move away from the backbone. This and assures that the barrel falls in a predictable manner preload is sufficient to hold the barrel tightly in place on so as to avoid harm to personnel or equipment from the the firearm, while also readily facilitating movement of 20 hot barrel. the barrel latch to release the barrel, when desired. As [0157] To release the barrel, the barrel latch is pushed those skilled in the art will appreciate, other configura- downwardly. Pushing the barrel latch downwardly moves tions of the swinging wedge and tensioner (such as the the swinging wedge so as to release the pin captured by preload provided thereby), can be likewise suitable. the swinging wedge. Once the pin is released, the barrel [0152] Thus, the swinging wedge wedges against the 25 is free to drop under the force of gravity. The barrel im- pin with approximately just amount that is necessary to mediately falls slightly, is pushed forward by the camming hold barrel to the firearm. In this manner, only a minimal process, and drops away from the firearm. amount of force applied downwardly to the barrel latch [0158] A safety mechanism, including a safety selector tends to be required in order to release the barrel. That switch, can be configured to cam the trigger forward in a is, excessive force need not be applied to the barrel latch 30 manner that prevents actuation of the trigger. The safety so as to overcome excessive force applied by the swing- mechanism can be configured to prevent the bolt carrier ing wedge to the pin. from being released during open bolt operation of the [0153] The barrel can have an 8 degree angle formed firearm. This can, for example, inhibit unintended firing in an annular boss that extends radially therefrom and of the firearm when the firearm is dropped. The safety that is received within the rear v-block. This 8 degree35 mechanism can also lock the hammer to prevent actua- angle can assure a desired fit of the boss within the v- tion thereof. block while inhibiting forward and reverse movement of [0159] According to an embodiment, many of the in- the barrel within the v-block. Thus, the 8 degree angle ternal working components of the firearm can be part of readily facilitates installation and removal of the barrel a common assembly. For example, the trigger group, the into the v-block while substantially inhibiting longitudinal 40 selector switch, the safety switch, the trigger lock out movement of barrel with respect to the v-block. The for- (keeps trigger from being pulled when the charge handle ward v-block can lack such an angle. The forward v-block is pulled back), etc., can be part of a trigger block assem- can be configured to facilitate some amount of longitudi- bly. nal movement of the barrel, so as to accommodate ther- [0160] Thus, at least some of the internal workings of mal expansion of the barrel. 45 the firearm can be attached to, contained within, and/or [0154] According to an embodiment, the ability to mounted upon a common structure or framework to de- quickly change the barrel while maintaining accuracy of fine the trigger block assembly. The use of the trigger fire without requiring re-zeroing of the sights is provided. block assembly facilitates the assembling of these com- The accuracy is maintained, at least in part, by the use ponents outside of the firearm. Once assembled, the of the v-blocks and the tensioner. The v-blocks and the 50 components can be dropped into the firearm, e.g., the tensioner cooperate to provide a rigid mount that brings lower receiver, and then secured in place, such as with a new barrel substantially into the same alignment as the one or more pins, screws, or other fasteners. old barrel. [0161] As those skilled in the art will appreciate, the [0155] According to an embodiment, as the barrel is assembly of such small, intricate components within the released it undergoes a two stage camming process. 55 lower receiver can be difficult, time consuming, and re- During the first stage of the camming process, the barrel quire a substantial amount of skill. Thus, such assembly is moved forward slightly (about one wall thickness of the can be comparatively expensive. By way of contrast, as- barrel).During the secondstage of thecamming process, sembly of the same parts outside of the lower receiver

19 37 EP 2 663 826 B1 38 can be substantially less difficult, substantially less time barrel) toward the backbone as the new barrel is attached consuming, and require substantially less skill. As such, to the firearm. assembling the trigger block assembly outside of the low- [0168] According to an embodiment, a selector mech- er receiver and then dropping the trigger block assembly anism can be used to select between closed bolt opera- into thelower receiverto facilitateassembly of these com- 5 tion and open bolt operation in the semi-automatic rifle ponents can be advantageous. and in the semi-automatic rifle/machine gun. The ma- [0162] According to an embodiment, two gas piston chine gun can be configured to fire from the open bolt rings are configured to be received at least partially within only. a groove of the piston. A key can be formed upon each [0169] The selector mechanism can be configured of the rings and a gap that is generally complimentary to 10 such that changing the selection from closed bolt to open the key can be formed in each of the rings. Thus, the gap bolt merely involves moving a selector lever. The selector of one ring can be configured to receive at least a portion mechanism can be configured such that changing the of the key of another ring. In this manner, the rings can selection from open bolt to closed bolt requires an extra be interlocked such that they cannot rotate to a position step. For example, changing the selection from open bolt where gaps in the rings line up in a manner that allows 15 to closed bolt can require that a button be depressed. hot gasses to flow through the gaps. The button can be part of the selector switch or can be [0163] As those skilled in the art will appreciate, when separate therefrom. For example, the button can be in the hot gases flow through the gaps, the force provided the middle of the selector switch. by the gases to extract the spent case and to chamber [0170] Requiring that an extra step be performed in a new cartridge is undesirably reduced. Further, when 20 order to change from open bolt operation to closed bolt the hot gases flow through the gaps, the hot gases can operation helps to assure that proper consideration is burn the ends of the rings and thereby undesirably en- given regarding the propriety of this change. As those large the gaps. skilled in the art will appreciate, changing from open bolt [0164] According to an embodiment, wings or protru- operation to closed bolt operation can result in a danger- sions 121 can be formed upon the gas piston and the 25 ous cookoff if a round is chambered while the chamber protrusions can slid within guide slots 122 of the cylinder. is hot. For example, a cookoff can occur if a round is The wings can cooperate with the guide slots to maintain chambered before the chamber has cooled adequately a desired orientation of the piston, e.g., to inhibit rotation after sustained rapid firing of the firearm. Cookoffs are of the piston. The wings can limit rearward motion of the not likely to occur during open bolt operation since the gas piston. The wings can limit rearward motion of piston 30 cartridge is fired as soon as it is chambered. Thus, this by abutting a forward end of backbone. The wings also extra step when changing from open bolt operation to facilitate easy installation and removal of the gas piston closed bolt operation is a desirable safety feature. The within the cylinder. A stop or other mechanism can sim- extra step can cause a user to more carefully consider ilarly be used to limit rearward motion of the gas piston. whether or not the chamber has had adequate time to [0165] According to an embodiment, the gas piston is 35 cool. not attached to an operating rod. The gas system of the [0171] It is common practice to pull the trigger of a fire- firearm can be configured such that a rear surface of the arm and to ease the bolt forward so as to avoid making gas piston strikes a forward surface of the bolt carrier so noise that may alert an enemy to the user’s presence. as to cause the bolt carrier to move rearward during cy- For example, a soldier using the M16 may be taught this cling of the firearm. Since the gas piston is not attached 40 technique. According to an embodiment, when firing from to an operating rod, the gas piston, as well as the rings a closedbolt, the user canpull triggerto easebolt forward. thereof, is easy to change. That is, the gas piston does Thus, the user can ease the bolt forward in a manner that not have to be removed from a connecting rod in order more quietly chambers a round so as to make detection to change the gas piston and/or the rings of the gas pis- by an enemy less likely. ton. 45 [0172] However, it may not be appropriate to move the [0166] According to an embodiment, the slots within bolt from an open position to a closed position, as dis- which the wings move also define gas vents that exhaust cussed herein. According to an embodiment, when firing gas from the cylinder to the atmosphere. Cover plates from the open bolt the trigger cannot be pulled to ease formed upon the forward end of the backbone can define bolt forward unless a button pushed. When firing from an a gas port flash suppressor that can obscure flash from 50 open bolt, the bolt should remain open (rearward) so as the slots so as to make such flash less visible and also to readily facilitate firing of the firearm and so as to better so as to mitigate the potential for injury from the exhaust- facilitate cooling of the chamber. ed hot gas. [0173] According to an embodiment, a main spring [0167] The gas port flash suppressor can be defined guide contains and/or at least partially defines an anti- by two flanges that substantially cover the slots. The55 bounce mechanism that mitigates undesirable bouncing flanges can also guide the new barrel as the new barrel of the bolt backwards after the bolt chambers a round. is being installed, such as during a barrel change. The As those skilled in the art will appreciate, bouncing of the flanges can guide the cylinder (which is attached to the bolt is undesirable because bouncing of the bolt may al-

20 39 EP 2 663 826 B1 40 low the hammer to strike the firing pin when the bolt is the hammer. As the bolt carrier moves forward when gun not fully forward, thus resulting in a light strike and a po- is fired, the bolt carrier uncovers hammer. The hammer tential misfire. does not begin to move (to fire the round) until bolt carrier [0174] A weight of the main spring guide can strike the is almost all the way forward. The hammer strikes the bolt in a manner that tends to mitigate bouncing thereof. 5 firing pin at approximately the same time as the bolt is The main spring can push the weight forward, along with locked or after the bolt is locked. the bolt carrier. For example, the weight can strike the [0181] Since the bolt carrier rides upon the hammer bolt and push the bolt forward just after the bolt chambers and holds the hammer down and under the bolt carrier, a round, e.g. just after the bolt has started to bounce. In the bolt carrier does not have to continually push the ham- this manner, the bolt is inhibited from bouncing rearward 10 mer down to maintain this cocked position. Rather, the as far as it otherwise would. The weight can be held rear- hammer is trapped beneath the bolt carrier and cannot ward prior to the bolt chambering a round by an anti- move (so as to fire a chambered cartridge) until the bolt bounce weight spring (different from the main spring). first moves forward. When the bolt moves forward, the [0175] The weight can be configured to slide along a hammerswings over the last round stop, with the hammer portion, e.g., proximate the forward end, of the main15 motion being at least partially constrained and defined spring guide. The weight can generally surround the main by the hammer link. spring guide. The weight can be disposed between the [0182] The hammer can be an aluminum hammer hav- main spring and the anti-bounce weight spring such that ing a steel face. The hammer can be all steel. The ham- the main spring biases the weight forward and the anti- mer can be comprised of aluminum, titanium, steel, or bounce weigh spring biases the weight rearward. 20 any combination thereof. The hammer can be made of [0176] Thus, the main spring serves two functions. The any desired material. main spring pushes the bolt carrier forward during cycling [0183] The hammer can be hard anodized where the of thefirearm and the mainspring pushesthe anti-bounce bolt carrier slides against the hammer. The hammer can weight forward, as well. Putting the anti-bounce weight be hardened or treated as desired where the bolt carrier on the main spring guide solve the problem of where to 25 slides against the hammer or on any other part or surface put the anti-bounce weight and allows the main spring thereof. and main spring guide to serve two functions, i.e., cycling [0184] According to an embodiment, a stock has the bolt carrier and inhibiting undesirable bouncing of the grooves formed in the butt thereof to define a handle. bolt. The grooves can define a hand grip that enhances a us- [0177] A gap can be provided between the anti-bounce 30 er’s ability to securely hold the stock when firing the fire- weight and a stop formed on the spring guide. The length arm with a bipod from a prone position. For example, one of this gap and the strength of the anti-bounce weight or more horizontal grooves formed in the butt can sub- spring can define the time at which the anti-bounce stantially inhibit vertical movement of stock with respect weight strikes the stop (and thus effectively strikes the to a user’s hand. That is, such grooves can inhibit unde- bolt). Thus, the gap can be configured so as to minimize 35 sirable slipping of the butt when the butt is grasped while undesirable bolt bounce. One or more, e.g., two, tabs shooting of the firearm. can retain the anti-bounce weight spring in place upon [0185] For example, one of the grooves can be formed the spring guide. to define a handle and so as to receive a user’s thumb [0178] According to an embodiment, a hammer as- when firing the firearm with a bipod from a prone position. sembly has a link. One end of the link is pivotally attached 40 Grasping the butt of the firearm with the user’s thumb in to the lower receiver and other end of the link is attached thegroove can bedone suchthat the groove substantially to the hammer. A spring guide can be pivotally attached inhibits undesirable slipping of the user’s thumb there- to lower receiver and received within a bore of hammer from. such that a spring on the spring guide biases the hammer [0186] The stock can be a folding stock, a collapsible to actuatedposition (a position thatresult in around being 45 stock, and/or a removable stock. The stock can be a rigid fired). stock that does not fold or collapse and that is not readily [0179] The use of the link provides a configuration removable. The stock can be any desired type of stock. wherein the hammer has a comparatively long travel and [0187] According to an embodiment, a metered gas a comparatively long reach. This long travel and long port is provided. The metered gas port can be separate reach allows the hammer to move over last round stop 50 from the gas port formed in the barrel. The metered gas 4011 (Figure 11J). This long travel and a long reach allow port, rather than the gas port formed in the barrel, deter- the bolt to be positioned more forward when a round is mines the amount of gas that is used to cycle the firearm. chambered. Thus, as the gas port that is formed in the barrel enlarges [0180] As bolt carrier retracts (such as when cocking over time due to the erosive effects of the hot gases ther- or shooting the firearm), the bolt carrier pushes the ham- 55 eon, operation of the firearm, such as cycling time, is not mer rearward to cock the hammer. At a point in the rear- substantially affected. The metered gas port can be in a ward travel of the bolt carrier, the bolt carrier pushes the gas block that is part of the sight mount of the firearm, hammer downward and then the bolt carrier rides over for example.

21 41 EP 2 663 826 B1 42

[0188] The metered gas port can be adjustable, so as forward, the bar is pulled forward by the bolt carrier to to compensate for erosion of the gas port in the barrel pull it away from the flat on the takedown latch pin. and so as to provide some degree of control of the fire- [0195] The semi-automatic rifle and the rifle/machine arm’s operation, e.g., the cyclic rate of the firearm. The gun can fire from the closed bolt (if closed bolt operation metered gas port can be easily changeable. A gas port 5 is selected). The semi-automatic rifle and the rifle/ma- rebuild kit that includes a new metered gas port can be chine gun can have a hammer to facilitate firing from the provided. Thus, more uniform cycling and enhanced re- closed bolt. The bar can be configured to prevent the liability of the firearm can be provided. hammer from being released until the bolt is all of the [0189] According to an embodiment, the metered gas way forward or almost all of the way forward, so as to port can comprise two tubular members that interlock 10 assure that the bolt is locked when the firearm fires. Dur- within a gas block of the firearm. For example, the me- ing semi-automatic fire, the bar can allow the bolt to lock tered gas port can comprise a first tubular member that before the hammer strikes the firing pin. During fully au- is inserted into the gas block and a second tubular mem- tomatic fire, the trigger may remain in the pulled position ber that is inserted into the gas block and into the first while the firearm continues to shoot, so the bar delays tubular member. 15 the hammer until the bolt has moved forward sufficiently. [0190] A screw, such as a set screw, can be screwed [0196] The same barcan perform bothfunctions. Thus, into the first tubular member to lock the first tubular mem- the same bar can prevent disassembly of the firearm ber to the second tubular member and to lock the first when the main spring is fully compressed and can pre- tubular member and the second tubular member into the vent the hammer from being released prematurely. gas block. Turning the screw adjusts gas flow. 20 [0197] According to an embodiment, the takedown le- [0191] According to an embodiment, a heavy duty ex- ver has safety lock pin to prevent inadvertent turning of tractor can be used to extract spent cartridges from the the takedown lever to takedown position thereof and has chamber. The heavy duty extractor can grip more of the safety lockpin to prevent inadvertentlyturning of the take- spent cartridge than a contemporary extractor. The down lever to the non-takedown position thereof before heavy duty extractor can be thicker, heavier, and wider 25 firearm is reassembled. Both of these functions can be than a contemporary extractor. The heavy duty extractor performed by same safety lock pin. can have two pins and two springs that bias the extractor [0198] According to an embodiment, recoil can be mit- in position for gripping a spent cartridge, as opposed to igated as described in U.S. patent no. 4,475,438 issued the single pin and spring that is common in contemporary to Leroy J. Sullivan on October 9, 1984. According to this firearms. Thus, more reliable extraction is facilitated. 30 method, the impulse caused by shooting the firearm is [0192] According to an embodiment, a bar extends extended in time so as to substantially extend throughout substantially along the backbone above the bolt carrier. an entire cycle period of the firearm. The bar can prevent disassembly, i.e., takedown of the [0199] A dust cover can open approximately 7 degrees firearm with main spring fully compressed. The bar can to allow the charging handle to move backwards. Moving prevent takedown by interfering with operation of the35 thecharging handle backwards, e.g., cockingthe firearm, takedown lever when the bolt is in the open position (and can cause the dust cover to open. If the charging handle thus when the main spring is fully compressed). As those is not in its forwardmost position, the trigger cannot be skilled in the art will appreciate, takedown of a firearm pulled. with the main spring fully compressed can result the main [0200] According to an embodiment, the machine gun spring quickly and unexpectedly extending in a manner 40 does not have a hammer. The machine gun can have a than can cause injury. firing pin retaining pin that is configured to facilitate re- [0193] A downwardly extending tab formed proximate moval of the fire pin and is configured to transfer forward a front end of the bar can extend downwardly into a movement of the bolt carrier to the fire pin to cause a groove formed on the bolt carrier when the bolt carrier is cartridge to fire. Removal of the firing pin retaining pin near the forwardmost position thereof (and the main45 allows the firing pin to be removed. When the bolt carrier spring is thus not fully compressed). When the bolt carrier moves forward, the firing pin retainer pin causes the firing moves further forward, the tab can abut the end of the pin to move forward. groove and the bolt carrier can pull the bar forward such [0201] According to an embodiment, the cam pin can that the bar no longer interferes with the operation of the have a vertical hole formed therein that receives the firing takedown lever. Thus, when the bolt carrier is fully for- 50 pin tip to aid in removal of the cam pin. Thus, the cam ward, the takedown lever can be actuated to effect dis- pin can be removed by putting the tip of the firing pin in assembly of the firearm. the hole in the cam pin. The tip of the firing pin can be [0194] More particularly, a surface of the bar can con- put into the cam pin hole to aid in assembly, as well. tact a flat surface of the takedown lever pin when the bar [0202] According to an embodiment, for the machine is at a rearmost position thereof. When the flat surface 55 gun, the camming surface of the open bolt arm can be of the bar contacts the flat surface of the takedown lever, driven against the disconnector camming surface by the the takedown lever is prevented from rotating to the take- bolt carrier acting on the sear. This can be done while down position thereof. That is, when the bolt carrier is the open bolt arm is still being driven by the bolt carrier.

22 43 EP 2 663 826 B1 44

[0203] Features from one type of firearm described barrel lugs, and prevents locking motion (in this case the herein can be used in another type of firearm described bolts rotation) until the bolt has reached lock position and herein, as desired. Additional features can be added to then allows the bolt to lock to the barrel. The backbone any of the types of firearms described herein. Features differs from contemporary receivers, for example, in that can be removed, disabled, or not used in any desired 5 the backbone does not contain or surround the bolt it is type of firearm described herein. Thus, the features de- guiding. Instead both the bolt and the barrel assemblies scribe in conjunction with each type of firearm can be are outside and below the backbone, which at least par- mixed and matched as desired and are by way of exam- tially contains and at least partially guides the bolt carrier. ple only, and not by way of limitation. As viewed from the rear, the bolt carrier can be configured [0204] Certain embodiments described above illus- 10 as a thin waisted "figure 8". trate, but do not limit, the invention as claimed. It should [0208] As seen from the side, the upper part of the bolt also be understood that numerous modifications and var- carrier’s "figure 8" is a long tubular section with fore and iations are possible in accordance with the principles of aft contact points that center it within the backbone. This the present invention. Accordingly, the scope of the in- upper section of the bolt carrier slides fore and aft within vention is defined only by the following claims. 15 the backbone and contains the main spring. [0205] One or more embodiments provide a magazine [0209] A guide slot in the bottom of the backbone can fed, gas operated auto cycling firearm which operates be cut from the rear to approximately the middle of the generally as follows. Like all breech loading repeaters, Backbone. This slot is the passage way for the bolt carrier they must perform eight ammunition handling functions waist, which is connected to the bolt carrier’s lower sec- between one shot and the next. It must feed, chamber, 20 tion. The slot permits the bolt carrier to slide, while keep- lock, fire, unlock, extract, eject the ammunition cartridge ing the lower section of the bolt carrier substantially in and cock the gun ready for the next cycle. The bolt group line with the barrel. is involved in all eight of these functions. As a main spring [0210] The lower section of the bolt carrier can be drives the bolt group forward it completes the feed by shorter than the upper section. The lower section of the pushing the top cartridge forward out of the magazine 25 bolt carrier can contain the bolt and can maintain the bolt and tilting the forward bullet end up a feed ramp and into in line with the barrel. the barrel chamber and by rotating the bolt head to lock [0211] A cam pin in the bolt can extends upward it and the cartridge into the barrel and then fires the car- through a helical cam slot in the lower carrier section. tridge. That completes the forward moving half of the bolt The top of the cam pin can be the same width as the cycle. 30 carrier waist and slides fore and aft in the backbone’s [0206] As the bullet moves through the barrel it passes guide slot, which can prevents the cam from rotating the a gas port hole drilled in the barrel wall through which bolt until the cam pin reaches the cutout. At that position, high pressure gas enters the cylinder and drives the pis- the bolt lugs can have entered between the barrel lugs ton rearward, thus throwing the bolt carrier rearward and and the bolt can be released by the cutout and rotated compressing the main spring. During the bolt carrier’s 35 to lock by the helical angle of the cam as the carrier com- first rearward motion a helical cam in the carrier rotates pletes its forward motion until stopped by the rear most the bolt head to unlock the bolt head from the barrel and surface of the barrel. then pulls the bolt head rearward for the rest of their com- [0212] Accordingto an embodiment, a backbone struc- bined rearward cycle. An extractor claw on the bolt head ture that facilitates precise quick barrel c hange is provid- pulls the fired cartridge case from the barrel chamber and 40 ed. When in place the barrel is below the backbone and an ejector strikes or pushes on the cartridge base oppo- the rearmost surface of the barrel is approximately mid- site the extractor, pivoting the cartridge around the ex- point on the length of the Backbone. tractor and out through an eject port in the gun structure. [0213] A barrel cross pin (Figure 52C) can be perma- The combined bolt head and bolt carrier’s continued rear- nently aligned parallel with the barrel lugs and held in ward motion uncovers the new top cartridge in the mag- 45 place by a strap (shown simplified in Figures 52 and 53) azine which feeds it upward into the bolt head’s return [0214] A swinging wedge (Figures 52A-53B) can draw path while the rearward moving carrier and bolt cocks the cross pin and barrel upward tight into v-blocks (Figure the spring loaded firing hammer and moves beyond (rear- 52C) and can draw a barrel lock flange up into a lock ward of) a bolt stop which is lifted up by the magazine notch (Figures 52C and 53C). The backbone and barrel follower after the last cartridge has fed from the magazine 50 assembly shown in Figures 53A-53C are thus held in a and which catches and holds the bolt and carrier group substantially "precise" location with respect to one an- rearward so that the empty magazine can then be re- other. "Precise" in this case means that any individual moved and replaced with a full one ready to resume fire barrel assembly can be repeatedly installed and removed without hand cocking the gun. A cocking handle can be from one gun assembly and will return to substantially provided in case of a misfire or other cycle malfunction. 55 the same position on that gun. Each barrel has a front [0207] One or more embodiments provide a tubular sight adjustment and a gas port adjustment so any backbone that guides the fore and aft motion of the bolt, number of barrels can be installed and "zeroed" to a gun aligns the bolt and its locking lugs with the barrel and and all will remain on target and will properly operate that

23 45 EP 2 663 826 B1 46 particular gun if exchanged with one another. In that way, further the wedge swings, the higher it lifts the pin and any particular gun can have many dedicated barrels in barrel until the barrel is drawn up tight against its "V" both 5.56 and 6.8 and in different weights and lengths, blocks. The wedge can thus provide a tight fit for any some with, some without attachments like suppressors dimensional tolerances variations in any number of bar- or 40mm launchers. The barrel, once installed, cannot 5 rels so it achieves a precision fit for rifle accuracy without move up, down or sideways, cannot shift fore and aft, the cost of extraordinary precise manufacturing toleranc- and cannot rotate. The locking lug patterns of both the es and without the loss of interchangeability. bolt and barrel are thus aligned within the combined tol- [0220] Gas operated firearms are undesirably subject erance of positioning surface on the backbone, bolt and to failures to extract. When a failure to extract occurs, a barrel. Adequate clearances are provided in the lug pat- 10 fired cartridge is not extracted completely from a chamber terns to accommodate the tolerances plus heat expan- of the firearm. Such failures to extract prevent the next sion. round from being chambered and thus jam the firearm. [0215] Two spring assemblies consisting of a plunger, [0221] In some firearms, the bolt can strip the next car- spring and plug are housed in the two accessory rails tridge from a magazine and can ram the next unfired that are fastened to either side of the backbone. The ac- 15 cartridge into the chambered or partially chambered car- cessory rails have a clearance slot to accommodate the tridge. In an open bolt operated firearm with swinging wedge arms, which reach through to engage fixed firing pin such as a , this can result both ends of the barrel cross pin. The angled wedge sur- in a dangerous slam fire of the next cartridge when it is faces on the swinging wedge are driven forward by the blocked from entering the chamber. force of the spring assemblies to draw the cross pin and 20 [0222] Such failures to extract can be caused by insuf- barrel upward and tight into the v-blocks. ficient spring force to keep the extractor closed. Such [0216] If the bolt group is forward with the bolt locked failures can also be caused by breakage of the extractor. to the barrel, then the swinging wedge blocker would hit For example, repeated use of the extractor can cause a the top of the upper bolt carrier so that the swinging stress crack to form in the extractor or its associated wedge can’t be swung to release or to load a barrel as- 25 spring. The stress crack can propagate until the extractor sembly. The swinging wedge can only be operated if the or spring is weak enough to break. This problem is par- bolt group is locked rearward as it is in the open bolt fire ticularly prevalent in fully automatic firearms, due to the position or when the bolt catch is activated automatically high number of cycles and more extreme heat experi- by the magazine follower as the last round is fired. Thus enced thereby. without further attention the user can exchange hot bar- 30 [0223] One problem is that there is insufficient spring rels for cool ones for maximum sustained fire. All the user force to keep the extractor closed due to extreme vibra- needs to do is hit the top plate of the swing wedge, such tion common in fully automatic firearms. According to an as with a "karate chop" like motion, and the hot barrel is embodiment, the extractor can be wider, have a wider ejected. No tools or protective gear are needed (such as claw, and can have more spring force that biases the to prevent burns). 35 extractor in a closed position so as to more firmly grasp [0217] The barrel assembly is designed for machine a cartridge being removed from the barrel. gun firepower. This means that 1500°F barrel heat and [0224] Figures 58-61 show an extractor 9100, in ac- the precise tight fit of the v-blocks and the swinging cordance with an embodiment. The extractor 9100 has wedge holding the cross pin can still accommodate the a generally "L" shape defined by an upper portion 9101 barrels increased size from heat expansion which will 40 and a lower portion 9102. The extractor 9100 also has a grow 0.229 mm (.009") bigger in diameter and 14.49 mm heel 9103, a claw 9104, and a bump 9105. (.057") in length between the v-blocks. If the strap shown [0225] The extractor 9100 has a closed position and in Figures 52 and 53 is used, either the strap, cross pin, an open position. The extractor 9100 is generally in the swing wedge, backbone, or barrel would be bent or se- closed position when the claw 9104 is not engaging an verely damaged by heat expansion. 45 absent cartridge. [0218] The tensioner shown in Figures 54A-55D can [0226] Spring force applied to the heel 9103 in the di- be subject to the bending from such expansion. The ten- rection indicated by arrow 9106 can cause the extractor sioner can be a spring that is strong enough (when its 9100 to pivot about the bump 9105. The spring force can force adjustment screw is initially set to 317.52 kg (700 be applied by two springs 9501, 9502 (Figure 67) that lbs.) of preload) to keep the barrel tight in the v- blocks, 50 cooperate with two plungers 9503, 9504 (Figure 67), so thus accommodating the vibration and shock of firing and as to bias the extractor 9100 in the closed position there- the off-center force of the gas system. Thereafter, the of. This biasing force causes the claw 9104 to more firmly tensioner’ s flexibility as the barrel expands downward grab or engage a cartridge. increases the force by 498.95 kg (1100 lbs.), which is far [0227] The extractor 9100 can also have a cutout 9107 too low of a force to permanently bend or damage the 55 that is configured to abut an extractor stop pin 9506 (Fig- parts involved. ure 67) to limit rearward movement of the extractor 9100, [0219] The swinging wedge can contact the bottom of as discussed herein. the pin at an angle of approximately 8 degrees. Thus the [0228] The extractor 9100 can also have a width, Di-

24 47 EP 2 663 826 B1 48 mension W, that is substantially greater that the width of [0237] For example, the bolt 9200 can have an eight a contemporary extractor. For example, the width, Di- lug pattern with one lug (the lug that would have been at mension W, of the extractor 9100 can be increased by the top of the pattern shown in Figure 64) removed so approximately 28% as compared to a contemporary ex- as to accommodate the width of the extractor 9100 and tractor. For example, the width, Dimension W, can be 5 to facilitate drilling of the two spring holes 9202, 9203 between approximately 6 mm and 8 mm and can be ap- side-by-side without their intermediate wall being com- proximately 7.77 mm. Thus, the extractor 9100 can be promised, e.g., being so thin as to break though. Removal stronger, more robust, and less susceptible to failures to of the lug can also better accommodate the installation extract with respect to contemporary extractors. of the springs 9501, 9502 and the plungers 9503, 9504 [0229] Figure 62 and 63 show a bolt 9200, in accord- 10 in the spring holes 9202, 9203. ance with an embodiment. The bolt 9200 can have a [0238] Figures 65 and 66 show cross-sectional views body 9201 within which is formed two spring holes 9202 of the bolt 9200, in accordance with an embodiment. An and 9203. Each spring hole 9202, 9203 can receive and extractor stop pin hole 9401 can be configured to receive retain one of the springs 9501, 9502 and one of the plung- an extractor stop pin 9506 (Figure 67). The extractor stop ers 9503, 9504. 15 pin hole 9401 can be formed at least partially within the [0230] Thus, the bolt 9200 can have two springs 9501, cavity 9204. The extractor stop pin hole 9401 can be 9502 in a side-by-side and generally parallel configura- formed proximate a rear of the cavity 9204. tion. The two springs 9501, 9502 can apply force to the [0239] The extractor stop pin 9506 can limit rearward heel 9103 of the extractor 9100 to bias the extractor 9100 movement of the extractor 9100. For example, the ex- into the closed position thereof. 20 tractor stop pin 9506 can limit rearward movement of the [0231] The two springs 9501, 9502 can apply greater extractor 9100 sufficiently to prevent the pivot bump 9105 force (as compared to a single such spring) to the ex- from escaping from the groove 9206. tractor 9100 so as to cause the extractor 9100 to better [0240] The claw 9104 defines a cam or ramp 9111 (Fig- engage the rim of a cartridge. Thus, the use of two springs ure 61) on a front surface thereof. For firearms having 9501, 9502 can mitigate failures to extract. 25 cartridges with deep extractor recesses, a comparatively [0232] The bolt 9200 can have a cavity 9204 formed steep ramp 9111 is required to lift the claw 9104 up and therein. The cavity 9204 can at least partially receive and over the rim. As the ramp 9111 becomes more steep, it retain the extractor 9100. The cavity 9204 can facilitate becomes more likely that the extractor 9100 will move installation of the springs 9501, 9502 and the plungers rearward rather than have the claw 9104 lift up, over the 9503, 9504 into the spring holes 9202, 9203. 30 cartridge rim, when the cartridge rim is pressed into the [0233] The cavity 9204 can be open on the top thereof. bolt face 9303 (Figure 64). By placing the extractor stop The cavity 9204 can be open on one side thereof and pin 9506 in the extractor stop pin hole 9401, this unde- closed on another side thereof. For example, the cavity sirable rearward movement of the extractor 9100 can be 9204 can have a wall 9511 on one side thereof and can mitigated. Thus, the extractor stop pin 9506 can help lack such a wall on the other side thereof. Having the 35 maintain the extractor 9100 in place during operation of cavity 9204 open on one side and closed on another side the firearm. thereof more readily facilitates manufacturing of the bolt [0241] The extractor stop pin 9506 can be installed in 9200 while maintaining a greater strength around the those bolts 9200 where it is needed, e.g., where a steep cavity 9204 than would exist without the wall 9511. ramp 9111 is present. The extractor stop pin 9506 can [0234] The cavity9204 can have a groove 9206 formed 40 be left out in those bolts 9200 where it is not needed, therein. The groove 9206 can receive the bump 9105 of e.g., where a steep ramp 9111 is not present. In either the extractor. The bump 9105 can cooperate with the instance, theextractor stop pin hole 9401 can be provided groove 9206 to define a pivot about which the extractor so that the extractor stop pin 9506 can be installed as 9100 (particularly the claw 9104 thereof) can rotate sev- needed. eral degrees. 45 [0242] A recess 9107 can be formed in the extractor [0235] The spring holes 9202, 9203 can be formed be- 9100 to partially receive the extractor stop pin 9506. The hind the cavity 9204. The spring holes 9202, 9203 can size, e.g. depth, of the recess 9107 can define the limit be approximately parallel with respect to one another. of rearward movement of the extractor 9100. The spring holes 9202, 9203 can be approximately par- [0243] Figures 67 and 68 show perspective views of allel with respect to a firing pin hole 9207, at least to within 50 the bolt 9200, in accordance with an embodiment. As approximately 5°. can be seen, each spring 9501, 9502 has a plunger 9503, [0236] Figure 64 show an end view of the bolt 9200, in 9504 in front thereof and the plunger 9503, 9504 can accordance with an embodiment. The bolt 9200 can have bear upon the heel 9103 of the extractor 9100. The force a bolt face 9303 formed at a front thereof. The bolt 9200 applied by the plungers 9503, 9504 can bias the extractor can have a plurality, e.g., seven, lugs 9301 formed ther- 55 9100 into a closed position wherein the claw 9104 of the eon. The lugs 9301 can rotate to lock the bolt 9200 to a extractor 9100 is closest to a centerline 9250 (Figure 62) corresponding plurality of lugs in the barrel prior to firing of the bolt 9200. The open position of the extractor 9100 a cartridge. can be considered to be a position wherein the claw 9104

25 49 EP 2 663 826 B1 50 is not closest to a centerline 9250, such as when the claw substantially in unison with one another, the gaps 7003 9104 ofthe extractor 9100 is engaging a rimof a cartridge. of the two piston rings 7001 cannot align with one anoth- [0244] The biasing force applied the springs 9501, er. Therefore, gas cannot easily flow past the two piston 9502 urges the bump 9105 of the extractor 9100 forward, rings7001 andan enhanced gas sealis provided thereby. into the groove 9206. The biasing force applied the5 [0254] Figures 72-74 show the gas metering port 7502, springs 9501, 9502 also urges the claw 9104 to pivot according to an embodiment. The gas metering port 7502 downwardly, such as into a recess defined in a cartridge can comprise a first tubular member 7511 that passes by the rim of the cartridge. Thus, when a cartridge has through a second tubular member 7512, wherein the first been chambered and the locking lugs 9301 of the bolt tubular member 5711 and the second tubular member 9200 are fully engaged (the bolt 9200 is locked), then the 10 7512 are held within the gas block 7503 via a screw 7513 claw 9104 of the extractor 9100 is engaged with the car- that screws into the second tubular member 7512. The tridge. The biasing force urges the extractor 9100 from screw 7513 can expand a portion of the second tubular an open position to a closed position thereof. member 7512 as the screw 7513 is tightened so as to [0245] An ejector hole 9514 can contain an ejector (not cause the second tubular member 7512 to frictionally en- shown) for pushing a fired cartridge from the lower re- 15 gage the gas block 7502. The amount of gas provided ceiver 102 of the firearm 9600 (Figure 6) as the bolt by the gas metering port 7502 can be set by adjusting moves rearward. the screw 7513. Turning the screw 7513 can vary the [0246] Drain holes 9214 facilitate the draining of fluids size of an opening 7515 though which the gas flows in from the spring holes 9202, 9203. If the assembled bolt the first tubular member 7511. 9200 is soaked in cleaning fluid, for example, then the 20 [0255] Gas flows from the barrel 105 through the barrel cleaning fluid can be drained from the spring holes 9202, gas port 7501, through passage 7561 formed in the gas 9203 via the drain holes 9214. Otherwise, the incom- block 7503, and into the first tubular member 5711. Gas pressible cleaning fluid may interfere with proper opera- flows though the opening 7515, past the screw 7513, and tion of the extractor 9100. into the cylinder 7004, where the gas can act upon the [0247] A camming surface 9215 can facilitate clocking 25 piston 7003. or rotation of the bolt 9200 to engage the lugs 9301. This [0256] Since the gas metering port is disposed outside can be done according to well known principles. of the barrel 105, the gas metering port 7502 is not subject [0248] Figure 69 is a flow chart showing operation of to erosion the way that the barrel gas port 7501 is subject the firearm in accordance with an embodiment. The fire- to erosion. Thus, the use of a gas metering port 7502 arm can be cycled by either cocking the firearm or by 30 better assures uniform operation of the firearm over an firing the firearm, as indicated in block 9701. When the extended time period. firearm is cycled, a new cartridge can be stripped from [0257] Figures 75-81 show a tensioner 8083 for pro- its magazine. viding a preload for the attachment of the barrel 105 to [0249] The ramp 9111 of the claw 9104 of the extractor the backbone 103. This preload is the amount of force 9100 can ramp over a rim of the cartridge, as indicated 35 with which the barrel 105 is held to the backbone 103. in block 9702. The extractor stop pin 9506 can limit rear- The preload assures that the barrel 105 is held tightly to ward movement of the extractor 9100 as the cartridge is the backbone 103. chambered. The extractor stop pin 9506 can be either [0258] Figure 75 is a side view of a barrel 105 posi- installed or omitted, as needed for a particular firearm. tioned for attachment to a backbone 103, according to [0250] The two springs 9501, 9502 can apply force to 40 an embodiment. The barrel 105 can be attached to the the extractor 9100 as the cartridge is extracted after firing backbone 103 by pressing the barrel latch 113 down- the firearm, as indicated in block 9703. The cycle can wardly (as indicated by the downward arrow) so as to then repeat. move the swinging wedge 8253 to the left such that the [0251] The use of a wider extractor provides enhanced swinging wedge 8253 can receive the pin 8254. The bar- engagement of the extractor with the rim of a cartridge 45 rel latch 113 and the swinging wedge 8253 can rotate to mitigate the occurrence of failures to extract. The use against spring tension about pivot pin 7581 (as indicated of two springs better facilitates forceful engagement of a by the counterclockwise curved arrow) when the level clawof the extractor with a rim ofa cartridge soas mitigate 113 is pressed downwardly. After the barrel latch 113 is the occurrence of failures to extract. pressed, the barrel 105 can be moved generally upwardly [0252] Figures 70 and 71 show two gas piston rings 50 (as indicated by the upward arrows). The ramp 8252 can 7001, according to an embodiment. Each piston ring function as a guide for the proximal end of the barrel 105 7001 has a key 7002 formed thereon. The key 7002 is during installation of the barrel 105. Distal end of the bar- configured to be received within a gap of a piston ring rel 105, e.g. the barrel extension 8606, can be seated 7001. Two piston rings 7001 can be nested or positioned prior to the pin 8254 being received by the swinging next to one another such that the key 7002 of each piston 55 wedge 8253. ring 7001 is received within the gap 7003 of each other [0259] Figure 76 is a side view of a barrel 105 attached piston ring 7002. to a backbone 103, according to an embodiment. Once [0253] Since the two piston rings 7001 can only rotate the barrel 105 is within the rear v-block 8081 and the front

26 51 EP 2 663 826 B1 52 v-block 8082 and once the flange 8087 of the barrel ex- in connection with only a limited number of embodiments, tension 8088 is within the groove 8086 of the rear v-block it should be readily understood that the invention is not 8081, then the barrel latch 113 can be released such that limited to such disclosed embodiments. Rather, the in- spring tension causes the swinging wedge 8253 to en- vention can be modified to incorporate any number of gage the pin 8254 so as to attach the barrel 105 to the 5 variations, alterations, substitutions or equivalent ar- backbone 103. rangements notheretofore described, but which are com- [0260] Figure 77 is a cross-sectional side view of the mensurate with the claims. Additionally, while various barrel 105 and backbone 103 taken along line 77 of Fig- embodiments of the invention have been described, it is ure 76, according to an embodiment. The rear v-block to be understood that aspects of the invention may in- 8081 contactsthe barrel105 overan arcof approximately 10 clude only some of the described embodiments. Accord- 120° on the top portion of the barrel 105. Figure 78 is a ingly, the invention is not to be seen as limited by the cross-sectional side view showing the barrel 105 and foregoing description, but is only limited by the scope of backbone 103 of Figure 77 exploded apart from one an- the appended claims. other, according to an embodiment. [0267] Within the scope of the wording of the claims [0261] Figure 79 is a cross-sectional side view of the 15 the firearm can comprise: a bolt carrier; a backbone con- barrel 105, backbone 103, swinging wedge 8253, and figured to guide the bolt carrier; a lower receiver within tensioner 8083 taken along line 79 of Figure 76, accord- which the bolt carrier is at least partially disposed, where- ing to an embodiment. Once the barrel 105 has been in the backbone is removably attached to the lower re- attached to the backbone 103, the tensioner 8083 main- ceiver; a barrel latch attached to the backbone; a barrel tains a preload that holds the barrel 105 securely to the 20 configured to disengage from the backbone when the backbone 103. For example, the tensioner 8083 can pro- barrel latch is pushed; a trigger block assembly config- vide a preload of approximately 700 pounds that holds ured to drop into the lower receiver; a gas piston having the barrel 105 to the backbone 103. a plurality of piston rings configured to only rotate sub- [0262] With particular reference to Figures 77-82, the stantially in unison with one another, wherein the gas tensioner 8083 can have a yoke 7901 that extends down- 25 piston is configured to move the bolt carrier when a car- wardly from the pin 8254. In response to the pin 8254 tridge is discharged; a metered gas port disposed out of being pulled upwardly by the swinging wedge 8253, the the barrel for metering gas from the barrel to the gas yoke 7901 can pull upwardly to compress spring washers piston;a springguide having a main spring disposed ther- 7902 when the barrel 105 is attached to the backbone eon for biasing the bolt carrier in a forward position; an 103. The compressed spring washers 7902 push up- 30 anti-bounce weight at least partially contained within the wardly against a threaded collar or flange 7903. The spring guide; a bolt carried by the bolt carrier; an extractor threaded flange 7903 has a screw 7904 threaded there- attached to the bolt; two springs disposed within the bolt through and contacting the barrel 105. The screw 7904 for biasing the extractor toward a closed position of the bears upon the barrel 105 and applies a preload gener- extractor; a bar inhibiting separation of the lower receiver ated by the compressed spring washers 7902 to the bar- 35 and the backbone when the main spring is compressed; rel 105. The amount of the preload is adjustable by turn- a firing pin disposed within the bolt; one of: a firing pin ing the screw 7904. retaining pin configured to facilitate removal of the firing [0263] A screw 7921 can attach the fore grip 106 to pin and configured to transfer forward movement of the the tensioner 8083 and thus to the firearm. The screw bolt carrier to the firing pin to cause a cartridge to fire and 7921 can thread into an extension 7922 that hangs down- 40 a hammer assembly disposed within the lower receiver wardly from the tensioner 8083. and having a hammer and a link with one end of the link [0264] Figure 83 shows which of the three firearms var- attached to the hammer and another end of the link at- ious different features can be found on. For example, tached to the lower receiver such that the hammer has open bolt full auto operation can be found on the machine a rearward position that is below the bolt when the bolt gun 100 and the rifle/machine gun 8000, as indicated in 45 is in a rearward position and the hammer has a forward line one of the chart. Features of the machine gun 100, position where the hammer strikes the firing pin when the semi-auto rifle 1000, and the rifle/machine 8000 can the bolt is in a forward position and wherein the link is be used on one another and on other firearms. Such fea- configured such that the hammer has sufficient throw to tures can be use alone, or on any desired combination, travel over a last round stop as the hammer moves from on any firearm. For example, the metered gas port 7602 50 the rearward position to the forward position wherein the and the extractor 9100 can be used on other firearms, link, not the hammer, has the notches actuated by a trig- such as the M16 and M4. ger motion; a takedown lever configured to inhibit sepa- [0265] The term "firearm" as used herein can refer to ration of the backbone and the lower receiver, the take- the machine gun 100, the semi-auto rifle 1000, and the down lever having a safety lock pin to inhibit inadvertent rifle/machine 8000. The term "firearm" as used herein 55 movement of the takedown lever; a charging handle con- can refer to other firearms, such as contemporary fire- figured to move rearward to move the bolt carrier from a arms. closed bolt position to an open bolt position; a dust cover [0266] While the invention has been described in detail configured to open partially to allow the charging handle

27 53 EP 2 663 826 B1 54 to move rearward and to block bolt release from open four surfaces for contacting a backbone that are forward bolt position until the cocking handle has returned for- on the bolt carrier and has four surface for contacting the ward; a gas port flash suppressor configured to guide the backbone that are aft on the bolt carrier. barrel during mating of the barrel to the backbone; and [0272] According to an embodiment, a firearm can a stock having a handle formed therein, wherein a pro- 5 have a barrel, a lower receiver, a backbone and two v- jection is configured to inhibit vertical movement of a blocks with a spring loaded 2-armed swinging wedge lo- stock. cated halfway between them and attached to the back- [0268] Within the scope of the wording of the claims bone to hold the barrel pulled up tight and precisely cen- the firearm can comprise: a bolt carrier; a backbone con- tered in the v-blocks with the flange of the barrel exten- figured to guide the bolt carrier; a lower receiver within 10 sion in a fore and aft locking groove in the rear v-block. which the bolt carrier is at least partially disposed, where- [0273] The rear v-block bears on and centers the body in the backbone is removably attached to the lower re- diameter of the barrel extension while the top 120° of the ceiver; a barrel latch attached to the backbone; a barrel flange of the barrel extension fits up into a locking groove configured to disengage from the backbone when the in that v-block. The close fit of the flange and locking barrel latch is pushed; and a trigger block assembly con- 15 groove combined with the upward pull of the swinging figured to drop into the lower receiver. wedge on the barrel cross pin holds the barrel centered [0269] Within the scope of the wording of the claims in the v-blocks, locks the barrel to the backbone and se- the firearm can comprise: a bolt carrier for a firearm; a curely blocks any fore and aft movement of the barrel backbone configured to at least partially guide the bolt breech in relation to the backbone structure. carrier as the bolt carrier moves forward and backward 20 [0274] Forlongitudinal heatexpansion the barrel slides during a firing cycle of the firearm; and wherein the bolt fore or aft in the front v-block and the swinging wedge carrier is not completely contained within the backbone; follows that motion without releasing its wedging force. wherein a portion of the bolt carrier is contained within [0275] For radial heat expansion the two upper arms the backbone and a portion of the bolt carrier is not con- of a "Y" shaped yoke fit around both sides of the barrel tainedwithin the backbone; whereinpart of the boltcarrier 25 and have a cross pin fastened through them across the hangs below the backbone; wherein part of the bolt car- top of the barrel. The ends of the cross pin extend beyond rier is slidably disposed within the backbone; wherein: the outer sides of the two arms so that the 2-armed swing- the backbone is generally tubular and has a slot formed ing wedge pulls upward on the two ends of the cross pin. longitudinally therein; the bolt carrier has an upper portion In the crotch of the yoke an adjustable set screw bears contained within the backbone, a lower portion not con- 30 on the bottom of the barrel and is factory adjusted to push tained within the backbone, and a waist interconnecting downward on a flanged threaded tube compressing high the upper portion and the lower portion; and wherein the force spring washers holding the yoke and cross pin waist is disposed within the slot and the upper portion downward with an initial force of approximately 317.52 moves longitudinally within the backbone; can comprise: kg (700 pounds). As the approximately 25.4 mm (1") bar- a bolt having a cam pin extending therefrom; wherein: 35 rel diameter expands from the heat of firing, the angled the bolt carrier comprises a cam for rotating the bolt by walls of the v-block force the barrel diameter downward, camming the cam pin; the backbone comprises a cutout the center of which moves downward about 0.1143 mm extending from one side of the slot; and a portion of the (.0045 inches) while the bottom compresses the spring cam pin extends into the slot to inhibit rotation of the bolt washers about 0.2286 mm (.009 inches) increasing the when the bolt carrier is in a rearward position, the portion 40 force to approximately 544.31 kg (1200 pounds) as the of the cam pin moves from the slot into the cutout to barrel temperature reaches approximately 815.5 °C facilitate camming of the cam pin and rotation of the bolt (1500° F). The barrel remains centered with no longitu- when the bolt is in a forward position, and the cam pin dinal breech movement. moves from the cutout into the slot when the carrier [0276] The bottom stem of the yoke is fastened through moves rearward; wherein the device is a firearm. 45 a fore grip. [0270] Within the scope of the wording of the claims [0277] To install a barrel it is lifted upward and pulled the firearm can comprise: a backbone disposed within rearward by its fore grip. Guide surfaces bring the barrel the receiver; a bolt carrier; and wherein movement of the extension into alignment with the locking groove and the bolt carrier is constrained by the backbone and is not cross pin into engagement with the swinging wedge constrained by the receiver. 50 which snaps onto the pin drawing the barrel tight upward [0271] Within the scope of the wording of claims 5, 6 into its V-blocks and locked into the groove. and 10 the firearm can comprise: a bolt carrier for a fire- [0278] To remove a barrel the barrel latch is hit down- arm, the bolt carrier having a generally tubular upper por- ward. The same guide surfaces that directed it into po- tion, a generally rectangular lower portion, and a waist sition guide it out and downward on a path that prevents interconnecting the upper portion and the lower portion; 55 it from hitting or damaging a magazine. That path is also and wherein the upper portion is substantially longer than not obstructed by the weapon’s bipod. the lower portion; wherein a front of the upper portion is [0279] Inthe firearmaccording to theclaims, the swing- forward of the lower portion; wherein the bolt carrier has ing wedge is configured to facilitate attachment of the

28 55 EP 2 663 826 B1 56 barrel to the backbone via the pin such that moving the that the hammer has a rearward position that is below barrel latch allows the barrel to detach from the back- the bolt when the bolt is in the rearward position and the bone; although not covered by the wording of the claims hammerhas a forward positionwhere thehammer strikes the swinging wedge can be configured such that approx- the firing pin when the bolt is in a forward position and imately the same force is applied to the barrel regardless 5 the link is configured such that the hammer has sufficient of where along the swinging wedge the pin contacts the throw to travel over a last round stop as the hammer swinging wedge; wherein the swinging wedge is curved; moves from the rearward position to the forward position wherein the swinging wedge is curved and a pivot of the and wherein the link, not the hammer, has sear notches swinging wedge is not concentric with a radius of the held and released by the trigger motion. swinging wedge; wherein the swinging wedge is curved 10 [0283] The firearm can, in accordance with claim 13, and a pivot of the swinging wedge is offset with respect comprise: a stock for said firearm. to a radius of the swinging wedge by an angle of approx- [0284] A gas operated firearm can additionally, al- imately 8°; can comprise: a tensioner for providing a though not covered by the claims, comprise: a barrel gas preload of the pin with respect to the swinging wedge; port formed in the barrel; a gas system; a metered gas and wherein the tensioner accommodates radial thermal 15 port not disposed in the barrel and configured to metered expansion of the barrel; can comprise a tensioner for gas from the barrel to the gas system; and wherein the providing a preload of approximately 317.52 KG (700 metered gas port tends to maintain a substantially uni- lbs.) for the pin with respect to the swinging wedge; can form quantity of gas to the gas system as the barrel gas comprise: two V-blocks attached to the backbone into port enlarges due to wear; wherein the metered gas port which the barrel is pulled by the swinging wedge; and 20 comprises an adjustment screw for varying the quantity wherein the V-blocks maintain alignment of the barrel of gas to the gas system; wherein the metered gas port with respect to the backbone while the a tensioner ac- comprises: a first tubular member; a second tubular commodates thermal expansion of the barrel; can com- member interlocking with the first tubular member; and prise: a first guide cam configured to move the barrel wherein gas flows through the first tubular member and forward beyond a front of the lower receiver to release 25 the second tubular member; can comprise: a gas block; the barrel from the backbone when a proximal end of the wherein the metered gas port comprises: a first tubular barrel latch is moved; and a second guide configured to member; a second tubular member interlocking with the swing the barrel forward of a magazine of the firearm so first tubular member; and wherein the first tubular mem- the barrel can drop away from the firearm without con- ber is inserted into the gas block of the firearm and the tacting the magazine; wherein the swinging wedge is de- 30 second tubular member is subsequently inserted into the fined by wedge surfaces formed in paws that are moved gasblock and intothe firsttubular member; can comprise: by a lever end of the barrel latch. a gas block; herein the metered gas port comprises: a [0280] The firearm inaccordance with claim 7 can com- first tubular member; a second tubular member interlock- prise: a trigger block assembly for a firearm; and wherein ing with the first tubular member; wherein the first tubular the trigger block assembly is configured to drop into the 35 member is inserted into the gas block of the firearm and firearm. the second tubular member is subsequently inserted into [0281] The firearm according to the claims can addi- the gas block and into the first tubular member; and a tionally, although not covered by the claims, comprise: a screw that screws into the first tubular member to lock recoil spring configured to be compressed by rearward the first tubular member to the second tubular member movement of a bolt carrier when a firearm is discharged; 40 and to lock the first tubular member and the second tu- a spring guide for limiting movement of the recoil spring; bular member into the gas block. an anti-bounce weight defined by at least a portion of the [0285] The extractor of the firearm in accordance with spring guide; and wherein the anti-bounce weight is con- claim 13 can additionally, although not covered by the figured to inhibit bouncing of a bolt carrier of the firearm; claims, have a closed position and an open position; two wherein: the spring guide comprises a rod and a sleeve 45 springs for biasing the extractor toward the closed posi- surrounding a portion of the rod; and timing for the anti- tion; and wherein the extractor is sufficiently wide to be bounce weight is at least partially determined by a dis- biasedby the two springs.The firearm can, inaccordance tance between the front end of the anti-bounce weight with claim 13, have a bolt. Although not covered by the and the inside of the front cap of the bolt carrier; where claims said bolt can comprise: a body; a firing pin hole the device is a firearm. 50 formed in the body. [0282] The firearm can comprise as claimed in claims [0286] The firearm of claim 1 can additionally, although 7 and 13 a lower receiver for a firearm; a bolt having a not covered by the claims, comprise: a recoil spring for forward position and a reward position; a firing pin dis- a firearm; a bolt carrier having a forward position and a posed substantially within the bolt; a hammer assembly rearward position, wherein the recoil spring biases the disposed within the lower receiver and having a hollow 55 bolt carrier in the forward position; a bar configured to be tubular hammer and a link; and wherein one end of the pulled forward by the bolt carrier as the bolt carrier cham- link is pivotally attached to the hammer and another end bers a cartridge; and wherein the bar is configured to of the link is pivotally attached to the lower receiver such inhibit takedown of the firearm when the bolt carrier is in

29 57 EP 2 663 826 B1 58 the rearward position thereof and the recoil spring is com- figured to slidably receive a portion of a bolt carrier pressed; wherein the bar releases a hammer of the fire- (111); a swinging wedge (8253) configured to en- arm when the bolt of the firearm is substantially fully for- gage the cross pin on the barrel (105) to pull the ward; wherein the bar releases a hammer of the firearm barrel (105) upward into the pair of v-blocks (8081, to strike a firing pin when the bolt of the firearm is locked; 5 8082) on the backbone (103) (103) and to pull the herein the device is a firearm. flange (8087) on the barrel extension (8088) upward [0287] In accordance with claims 1, 7 and 13 the fire- into the groove (8086) in the backbone (103) to cent- arm comprises a backbone for said firearm; a lower re- er the barrel (105) and lock the barrel extension ceiver for the firearm; a takedown lever having a first (8088)from fore and aft motion inrelation to the back- position and a second position, wherein when the take- 10 bone (103). down lever is in the first position separation of the back- bone from the lower receiver is facilitated and when the 2. A firearm according to Claim 1, further comprising a takedown lever is in the second position separation of tensioner (8083) configured to provide a preload of the backbone from the lower receiver is inhibited; and a the cross pin with respect to the swinging wedge safety lock pin inhibiting inadvertent movement of the 15 (8253) and accommodate radial thermal expansion takedown lever from the first position to the second po- of the barrel (105). sition and inhibiting inadvertent movement of the take- down lever from the second position to the first position; 3. The firearm as recited in Claim 1, wherein the back- wherein the device is a firearm. bone (103) is configured to at least partially guide [0288] The firearm can, in accordance with claim 13, 20 the bolt carrier (111) as the bolt carrier (111) moves comprise: a charging handle for a firearm; and a dust forward and backward during a firing cycle of the cover configured to open approximately 7° to allow the firearm. charging handle to move rearwards as the firearm is cocked. 4. The firearm as recited in Claim 1, 2 or 3, wherein: [0289] The firearm according to the claims can addi- 25 a bolt (8011) is not contained within the backbone tionally, although not covered by the claims, comprise: a (103). cylinder disposed in a backbone of a gas operated fire- arm; a gas exhaust port formed in the cylinder for ex- 5. The firearm as recited in Claim 1, 2, 3 or 4, wherein hausting gas from the cylinder; and a gas exhaust port the bolt carrier (111) has an upper portion (8073) flash suppressor configured to guide a barrel to the back- 30 and a lower portion (8074). bone to facilitate attachment of the barrel to the back- bone; wherein the device is a firearm. 6. The firearm as recited in Claim 1, wherein the bolt [0290] The firearm according to the claims can be a carrier (111) has four surfaces for contacting the semi- configured for both closed bolt backbone (103) that are forward on the bolt carrier operation and open bolt operation of the firearm. 35 (111) and has four surfaces for contacting the back- [0291] A firearm comprises in accordance with claims bone (103) that are aft on the bolt carrier (111). 1 and 7 a lower receiver; a backbone; wherein the lower receiver is attached to the backbone via two hook pivots; 7. The firearm as recited in Claim 1: although not covered by the claims the lower receiver can pivot downward approximately 40° from two back- 40 wherein the backbone (103) is configured to bone studs attached to the backbone; and wherein the guide the bolt carrier (111) ; lower receiver can be detached from the backbone when wherein the receiver comprises a lower receiver pivoted down approximately 20° or halfway where a gap within which the bolt carrier (111) is at least par- in the hook pivot allows the lower receiver to be lifted up tially disposed; and off the backbone studs. 45 wherein the backbone (103) is removably at- tached to the lower receiver; and a trigger block assembly is configured to drop Claims into the lower receiver.

1. A firearm comprising: 50 8. The firearm as recited in Claim 7, wherein a portion a barrel (105) having a barrel extension (8088), of the bolt carrier (111) is contained within the back- wherein the barrel extension (8088) has a flange bone (103) and a portion of the bolt carrier (111) is (8087); not contained within the backbone (103). a cross pin (8254) on the barrel (105); a backbone (103) disposed within a receiver (102) above the bar- 55 9. The firearm as recited in Claim 7, wherein part of the rel (105), wherein the backbone (103) has a slot bolt carrier (111) hangs below the backbone (103). (8072),a groove (8086), and a pair ofv-blocks (8081) formed therein, and wherein the slot (8072) is con- 10. The firearm as recited in Claim 7, wherein:

30 59 EP 2 663 826 B1 60

the backbone (103) is generally tubular and has two springs disposed within the bolt for biasing the slot formed longitudinally therein; the extractor toward a closed position of the ex- the bolt carrier (111) has an upper portion (8073) tractor (9100); contained within the backbone (103), a lower a bar inhibiting separation of the lower receiver portion (8074) not contained within the back- 5 and the backbone (103) when the main spring bone (103), and a waist (8075) interconnecting is compressed; the upper portion and the lower portion; and a firing pin (8044) disposed within the bolt; the waist is disposed within the slot (8072) and a takedown lever configured to inhibit separation the upper portion moves longitudinally within the of the backbone (103) and the lower receiver, backbone (103). 10 the takedown lever having a safety lock pin to inhibit inadvertent movement of the takedown 11. The firearm as recited in Claim 7, further comprising: lever; a charging handle configured to move rearward a bolt having a cam pin (8071) extending there- to move the bolt carrier (111) from a closed bolt from; 15 position to an open bolt position; wherein: a dust cover (12109) configured to open partially to allow the charging handle to move rearward the bolt carrier (111) comprises a cam for and to block bolt release from open bolt position rotating the bolt by camming the cam pin; until the cocking handle has returned forward; the backbone (103) comprises a cutout ex- 20 a gas port flash suppressor configured to guide tending from one side of the slot; and the barrel during mating of the barrel to the back- a portion of the cam pin extends into the slot bone (103); and to inhibit rotation of the bolt when the bolt a stock having a handle formed therein, wherein carrier (111) is in a rearward position, the aprojection is configured to inhibit vertical move- portion of the cam pin moves from the slot 25 ment of a stock; and into the cutout to facilitate camming of the at least one of: cam pin (8071) and rotation of the bolt when the bolt is in a forward position, and the cam a firing pin retaining pin configured to facil- pin (8071) moves from the cutout into the itate removal of the firing pin and configured slot when the bolt carrier (111) moves rear- 30 to transferforward movement of thebolt car- ward. rier (111) to the firing pin to cause a cartridge to fire; and 12. The firearm as recited in Claim 7, wherein: a hammer assembly (11107) disposed with- in the lower receiver and having a hammer the bolt carrier (111) has a generally tubular up- 35 and a link with one end of the link attached per portion (8073) a generally rectangular lower to the hammer and another end of the link portion (8074), and a waist (8075) interconnect- attached to the lower receiver such that the ing the upper portion and the lower portion; and hammer has a rearward position that is be- the upper portion is substantially longer than the low the bolt when the bolt is in a rearward lower portion. 40 position and the hammer has a forward po- sition where the hammer strikes the firing 13. The firearm as recited in Claim 7, further comprising: pin when the bolt is in a forward position and wherein the link is configured such that the a gas piston (7003) having a plurality of piston hammer has sufficient throw to travel over rings (7001) configured to only rotate substan- 45 alast round stop as the hammermoves from tially in unison with one another, wherein the gas the rearward position to the forward posi- piston (7003) is configured to move the bolt car- tion, wherein the link, not the hammer, has rier (111) when a cartridge is discharged; notches actuated by a trigger motion. a metered gas port (7501) disposed out of the barrel (105) for metering gas from the barrel to 50 14. The firearm of any of Claims 1, 7, or 13 wherein the the gas piston (7003); cross pin passes through both sides of an open top a spring guide having a main spring disposed of a Y-shaped yoke (7901) with a bottom that passes thereon for biasing the bolt carrier (111) in a for- under the barrel and supports a compressed spring ward position; (7902) configured to push upward on the barrel while an anti-bounce weight at least partially con-55 pulling the cross pin downward tight against the bar- tained within the spring guide (8352); rel to allow the barrel to expand due to heat gener- a bolt carried by the bolt carrier (111); ated by fully automatic sustained fire to allow an ex- an extractor attached to the bolt; panding diameter of the barrel in the pair of v-blocks

31 61 EP 2 663 826 B1 62

(8081) to move downward to further compress the schlussträger (111) vier Oberflächen zum Kontak- spring without disturbing a position or a hold of the tieren des Rückgrats (103) aufweist, die sich vorne swinging wedge on the cross pin. an dem Verschlussträger (111) befinden, und vier Oberflächen zum Kontaktieren des Rückgrats (103) 15. The firearm as recited in any of the preceding claims, 5 aufweist, die sich hinten an dem Verschlussträger wherein the firearm is a fully automatic firearm. (111) befinden.

7. Schusswaffe nach Anspruch 1: Patentansprüche 10 wobei das Rückgrat (103) dazu konfiguriert ist, 1. Schusswaffe, die Folgendes umfasst: den Verschlussträger (111) zu führen; wobei das Gehäuse ein unteres Gehäuse um- einen Lauf (105) mit einer Laufverlängerung fasst, in dem der Verschlussträger (111) min- (8088), wobei die Laufverlängerung (8088) ei- destens teilweise angeordnet ist; nen Flansch (8087) aufweist; 15 wobei das Rückgrat (103) abnehmbar an dem einen Querzapfen (8254) an dem Lauf (105); unteren Gehäuse angebracht ist; und einin einem Gehäuse(102) über demLauf (105) eine Abzugblockanordnung dazu konfiguriert ist angeordnetes Rückgrat (103), wobei das Rück- in das untere Gehäuse zu fallen. grat (103) einen Schlitz (8072) aufweist, eine Nut (8086) und ein Paar darin gebildete 20 8. Schusswaffe nach Anspruch 7, wobei ein Abschnitt Prismen (8081), und wobei der Schlitz (8072) des Verschlussträgers (111) in dem Rückgrat (103) dazu konfiguriert ist, einen Abschnitt eines Ver- aufgenommen ist und ein Abschnitt des Verschluss- schlussträgers (111) gleitfähig aufzunehmen; trägers (111) nicht in dem Rückgrat (103) aufgenom- einen Schwenkkeil (8253), der dazu konfiguriert men ist. ist, mit dem Querzapfen an dem Lauf (105) in 25 Eingriff zu treten, um den Lauf (105) nach oben 9. Schusswaffe nach Anspruch 7, wobei ein Teil des in das Paar Prismen (8081, 8082) an dem Rück- Verschlussträgers (111) unter dem Rückgrat (103) grat (103) zu ziehen und den Flansch (8087) an hängt. der Laufverlängerung (8088) nach oben in die Nut (8086) in dem Rückgrat (103) zu ziehen, um 30 10. Schusswaffe nach Anspruch 7, wobei: den Lauf (105) zu zentrieren und die Laufver- längerung (8088) gegen Vorwärts- und Rück- das Rückgrat (103) allgemein röhrenförmig ist wärtsbewegung in Bezug auf das Rückgrat und der Schlitz in Längsrichtung darin gebildet (103) zu sperren. ist; 35 der Verschlussträger (111) einen in dem Rück- 2. Schusswaffe nach Anspruch 1, weiter umfassend ei- grat (103) aufgenommenen oberen Abschnitt ne Spannvorrichtung (8083), die dazu konfiguriert (8073), einen nicht in dem Rückgrat (103) auf- ist, eine Vorbelastung des Querzapfens in Bezug auf genommenen unteren Abschnitt (8074) und ein den Schwenkkeil (8253) bereitzustellen und die ra- Mittelstück (8075), das den oberen und den un- diale Wärmeausdehnung des Laufs (105) aufzuneh- 40 teren Abschnitt verbindet, aufweist; und men. das Mittelstück in dem Schlitz (8072) angeord- net ist und sich der obere Abschnitt in Längs- 3. Schusswaffe nach Anspruch 1, wobei das Rückgrat richtung in dem Rückgrat (103) bewegt. (103) dazu konfiguriert ist, den Verschlussträger (111) mindestens teilweise zu führen, wenn sich der 45 11. Schusswaffe nach Anspruch 7, die weiter Folgendes Verschlussträger(111) während eines Schießzyklus umfasst: der Schusswaffe nach vorne und nach hinten be- wegt. einen Verschluss mit einem sich davon erstre- ckenden Exzenterbolzen (8071); 4. Schusswaffe nach Anspruch 1, 2 oder 3, wobei: 50 wobei: in dem Rückgrat (103) kein Verschluss (8011) auf- genommen ist. der Verschlussträger (111) einen Exzenter zum Drehen des Verschlusses durch Drü- 5. Schusswaffe nach Anspruch 1, 2, 3 oder 4, wobei cken des Exzenterbolzens umfasst; der Verschlussträger (111) einen oberen Abschnitt 55 das Rückgrat (103) einen Ausschnitt um- (8073) und einen unteren Abschnitt (8074) aufweist. fasst, der sich von einer Seite des Schlitzes erstreckt; und 6. Schusswaffe nach Anspruch 1, wobei der Ver- sich ein Abschnitt des Exzenterbolzens in

32 63 EP 2 663 826 B1 64

den Schlitz erstreckt, um die Drehung des unteren Gehäuses zu verhindern, wobei der Ta- Verschlusses zu verhindern, wenn sich der kedown-Hebeleinen Sicherheitsarretierstift auf- Verschlussträger (111) in einer hinteren weist, um die unbeabsichtigte Bewegung des Stellung befindet, wobei sich der Abschnitt Takedown-Hebels zu verhindern; des Exzenterbolzens aus dem Schlitz in 5 einen Durchladegriff, der dazu konfiguriert ist, den Ausschnitt bewegt, um das Drücken sich nach hinten zu bewegen, um den Ver- des Exzenterbolzens (8071) und die Dre- schlussträger (111) aus einer geschlossenen hung des Verschlusses zu ermöglichen, Verschlussstellung in eine offene Verschluss- wenn sich der Verschluss in einer vorderen stellung zu bewegen; Stellung befindet, und sich der Exzenterbol- 10 eine Staubabdeckung (12109), die dazu konfi- zen (8071) aus dem Ausschnitt in den guriert ist, sich teilweise zu öffnen, um zuzulas- Schlitz bewegt, wenn sich der Verschluss- sen, dass sich der Durchladegriff nach hinten träger (111) rückwärts bewegt. bewegt und die Verschlussfreigabe aus der of- fenen Verschlussstellung zu sperren, bis der La- 12. Schusswaffe nach Anspruch 7, wobei: 15 degriff nach vorne zurückgekehrt ist; einen Gaskanal-Feuerdämpfer, der dazu konfi- der Verschlussträger (111) einen allgemein röh- guriert ist, den Lauf während des Zusammenfü- renförmigen oberen Abschnitt (8073), einen all- gens des Laufs und des Rückgrats (103) zu füh- gemein rechteckigen unteren Abschnitt (8074) ren; und und ein Mittelstück (8075), das den oberen Ab- 20 einen Schaft mit einem darin gebildeten Griff, schnitt und den unteren Abschnitt verbindet, wobei ein Vorsprung dazu konfiguriert ist, die aufweist; und vertikale Bewegung eines Schafts zu verhin- der obere Abschnitt wesentlich länger ist als der dern; und untere Abschnitt. mindestens eines der Folgenden: 25 13. Schusswaffe nach Anspruch 7, die weiter Folgendes einen Zündstift-Haltestift, der dazu konfigu- umfasst: riert ist, das Entfernen des Zündstifts zu er- leichtern und dazu konfiguriert ist, die Vor- einen Gaskolben (7003) mit einer Vielzahl von wärtsbewegung des Verschlussträgers Kolbenringen (7001), die dazu konfiguriert sind, 30 (111) auf den Zündstift zu übertragen, um sich nur im Wesentlichen gemeinsam zu dre- zu bewirken, dass eine Patrone zündet; und hen, wobei der Gaskolben (7003) dazu konfigu- eine Hahnanordnung (11107), die in dem riert ist, den Verschlussträger (111) zu bewe- unteren Gehäuse angeordnet ist und einen gen, wenn eine Patrone ausgeworfen wird; Hahn und ein Verbindungsglied aufweist, einen aus dem Lauf (105) heraus angeordneten 35 wobei ein Ende des Verbindungsglieds mit Gasdosierkanal (7501) zum Dosieren von Gas dem Hahn verbunden ist und ein anders En- aus dem Lauf in den Gaskolben (7003); de des Verbindungsglieds mit dem unteren eine Federführung mit einer darauf angeordne- Gehäuse verbunden ist, sodass der Hahn ten Hauptfeder zum Vorspannen des Ver- eine hintere Stellung aufweist, die unter schlussträgers (111) in eine vordere Stellung; 40 dem Verschluss ist, wenn sich der Ver- ein mindestens teilweise in der Federführung schluss in einer hinteren Stellung befindet, (8352) aufgenommenes Stoßdämpfungsge- und der Hahn eine vordere Stellung auf- wicht; weist, in der der Hahn auf den Zündstift auf- einen von dem Verschlussträger (111) getrage- schlägt, wenn sich der Verschluss in einer nen Verschluss; 45 vorderen Stellung befindet, und wobei das einen an dem Verschluss angebrachten Extrak- Verbindungsglied derart konfiguriert ist, tor; dass der Hahn einen ausreichenden Hub zwei in dem Verschluss angeordnete Federn aufweist, um sich über eine Letzer-Schuss- zum Vorspannen des Extraktors in Richtung ei- Sperre zu bewegen, wenn sich der Hahn ner geschlossenen Stellung des Extraktors50 aus der hinteren Stellung in die vordere (9100); Stellung bewegt, wobei das Verbindungs- eine Stange, die die Trennung des unteren Ge- glied, nicht der Hahn, von einer Abzugbe- häuses und des Rückgrats (103) verhindert, wegung betätigte Kerben aufweist. wenn die Hauptfeder gestaucht ist; einen in dem Verschluss angeordneten Zünd- 55 14. Schusswaffe nach einem der Ansprüche 1, 7 oder stift (8044); 13, wobei der Querzapfen durch beide Seiten einer einen Takedown-Hebel, der dazu konfiguriert offenen Oberseite einer Y-förmigen Gabel (7901) ist, die Trennung des Rückgrats (103) und des verläuft, die einen Boden aufweist, der unter dem

33 65 EP 2 663 826 B1 66

Lauf verläuft und eine gestauchte Feder (7902) hält, l’ossature (103). die dazu konfiguriert ist, an dem Lauf nach oben zu drücken und gleichzeitig den Querzapfen nach un- 5. Arme à feu telle qu’elle est décrite dans la revendi- ten fest an den Lauf zu ziehen, um es dem Lauf zu cation 1, 2, 3 ou 4, dans laquelle le porte-culasse ermöglichen, sich infolge durch vollautomatisches 5 (111) a une partie supérieure (8073) et une partie andauerndes Feuer erzeugter Hitze auszudehnen, inférieure (8074). um zuzulassen, dass sich ein sich ausdehnender Durchmesser des Laufs in dem Paar Prismen (8081) 6. Arme à feu telle qu’elle est décrite dans la revendi- nach unten bewegt, um die Feder weiter zu stau- cation 1, dans laquelle le porte-culasse (111) a qua- chen, ohne eine Stellung oder einen Halt des10 tre surfaces pour entrer en contact avec l’ossature Schwenkkeils an dem Querzapfen zu stören. (103) qui sont vers l’avant sur le porte-culasse (111) et a quatre surfaces pour entrer en contact avec l’os- 15. Schusswaffe nach einem der vorangehenden An- sature (103) qui sont vers l’arrière sur le porte-cu- sprüche, wobei es sich bei der Schusswaffe um eine lasse (111). vollautomatische Schusswaffe handelt. 15 7. Arme à feu telle qu’elle est décrite dans la revendi- cation 1 : Revendications dans laquelle l’ossature (103) est configurée 1. Arme à feu comprenant : 20 pour guider le porte-culasse (111) ; un canon (105) ayant une rallonge de canon (8088), dans laquelle le récepteur comprend un récep- dans laquelle la rallonge de canon (8088) a une bride teur inférieur au sein duquel le porte-culasse (8087) ; (111) est au moins partiellement disposé ; une tige transversale (8254) sur le canon (105) ; dans laquelle l’ossature (103) est attachée de une ossature (103) disposée au sein d’un récepteur 25 manière amovible au récepteur inférieur ; et (102) au-dessus du canon (105), dans laquelle l’os- un assemblage formant bloc détente est confi- sature (103) a une fente (8072), guré pour s’abaisser jusque dans le récepteur une gorge (8086), et une paire de vés (8081) formée inférieur. dans celle-ci, et dans laquelle la fente (8072) est configurée pour re- 30 8. Arme à feu telle qu’elle est décrite dans la revendi- cevoir de manière coulissante une partie d’un porte- cation 7, dans laquelle une partie du porte-culasse culasse (111) ; (111) est contenue au sein de l’ossature (103) et une une cale basculante (8253) configurée pour entrer partie du porte-culasse (111) n’est pas contenue au en prise avec la tige transversale sur le canon (105) sein de l’ossature (103). pour tirer le canon (105) vers le haut jusque dans la 35 paire de vés (8081, 8082) sur l’ossature (103) pour 9. Arme à feu telle qu’elle est décrite dans la revendi- tirer la bride (8087) sur la rallonge de canon (8088) cation 7, dans laquelle une partie du porte-culasse vers le haut jusque dans la gorge (8086) dans l’os- (111) est suspendue au-dessous de l’ossature sature (103) pour centrer le canon (105) et verrouiller (103). la rallonge de canon (8088) contre un mouvement 40 de va-et-vient par rapport à l’ossature (103). 10. Arme à feu telle qu’elle est décrite dans la revendi- cation 7, dans laquelle : 2. Arme à feu selon la revendication 1, comprenant en outre un tendeur (8083) configuré pour fournir une l’ossature (103) est tubulaire de manière géné- précharge de la tige transversale par rapport à la 45 rale et a la fente formée dans celle-ci de manière cale basculante (8253) et recevoir la dilatation ther- longitudinale ; mique radiale du canon (105). le porte-culasse (111) a une partie supérieure (8073)contenue au seinde l’ossature (103), une 3. Arme à feu telle qu’elle est décrite dans la revendi- partie inférieure (8074) non contenue au sein de cation 1, dans laquelle l’ossature (103) est configu- 50 l’ossature (103), et un rétrécissement (8075) in- rée pour guider au moins partiellement le porte-cu- terconnectant la partie supérieure et la partie lasse (111) alors que le porte-culasse (111) se dé- inférieure ; et place en avant et en arrière pendant un cycle de tir le rétrécissement est disposé au sein de la fente de l’arme à feu. (8072) et la partie supérieure se déplace de ma- 55 nière longitudinale au sein de l’ossature (103). 4. Arme à feu telle qu’elle est décrite dans la revendi- cation 1, 2 ou 3, dans laquelle : 11. Arme à feu telle qu’elle est décrite dans la revendi- une culasse (8011) n’est pas contenue au sein de cation 7, comprenant en outre :

34 67 EP 2 663 826 B1 68

une culasse ayant un axe de came (8071) inférieur et de l’ossature (103) quand le ressort s’étendant depuis celle-ci ; principal est comprimé ; dans laquelle : un percuteur (8044) disposé au sein de la culasse ; le porte-culasse (111) comprend une came 5 un levier de démontage configuré pour inhiber pour faire tourner la culasse par une la séparation de l’ossature (103) et du récepteur de came de l’axe de came ; inférieur, le levier de démontage ayant une gou- l’ossature (103) comprend une découpe pille de verrouillage de sécurité pour inhiber le s’étendant depuis un côté de la fente ; et mouvement par inadvertance du levier de une partie de l’axe de came s’étend jusque 10 démontage ; dans la fente pour inhiber la rotation de la une poignée de chargement configurée pour re- culasse quand le porte-culasse (111) est culer pour déplacer le porte-culasse (111) d’une dans une position reculée, la partie de l’axe position de culasse fermée à une position de de came se déplace de la fente jusque dans culasse ouverte ; la découpe pour faciliter l’action de came 15 une protection anti-poussière (12109) configu- de l’axe de came (8071) et la rotation de la rée pour s’ouvrir partiellement pour permettre à culasse quand la culasse est dans une po- la poignée de chargement de reculer et pour blo- sition avancée, et l’axe de came (8071) se quer le dégagement de la culasse de la position déplace de la découpe jusque dans la fente de culasse ouverte jusqu’à ce que le levier d’ar- quand le porte-culasse (111) recule vers 20 mement soit revenu en avant ; l’arrière. un cache-flamme d’orifice de gaz configuré pour guider le canon pendant l’accouplement du ca- 12. Arme à feu telle qu’elle est décrite dans la revendi- non et de l’ossature (103) ; et cation 7, dans laquelle : une crosse ayant une poignée formée dans cel- 25 le-ci, dans laquelle une saillie est configurée le porte-culasse (111) a une partie supérieure pour inhiber le mouvement vertical d’une tubulaire de manière générale (8073), une partie crosse ; et inférieure rectangulaire de manière générale au moins un élément parmi : (8074), et un rétrécissement (8075) intercon- nectant la partie supérieure et la partie30 une goupille de retenue de percuteur con- inférieure ; et figurée pour faciliter le retrait du percuteur la partie supérieure est substantiellement plus et configurée pour transmettre le mouve- longue que la partie inférieure. ment en avant du porte-culasse (111) au percuteur pour amener une cartouche à 13. Arme à feu telle qu’elle est décrite dans la revendi- 35 tirer ; et cation 7, comprenant en outre : un assemblage formant chien (11107) dis- posé au sein du récepteur inférieur et ayant un piston à gaz (7003) ayant une pluralité de un chien et une liaison avec une extrémité segments de piston (7001) configurés pour tour- de la liaison attachée au chien et une autre ner seulement substantiellement à l’unisson les 40 extrémité de la liaison attachée au récep- uns avec les autres, dans laquelle le piston à teur inférieur de sorte que le chien a une gaz (7003) est configuré pour déplacer le porte- position reculée qui est au-dessous de la culasse (111) quand une cartouche est culasse quand la culasse est dans une po- déchargée ; sition reculée et le chien a une position un orifice de gaz mesuré (7501) disposé hors 45 avancée quand le chien frappe le percuteur du canon (105) pour mesurer le gaz du canon quand la culasse est en positon avancée et au piston à gaz (7003) ; dans laquelle la liaison est configurée de un guide de ressort ayant un ressort principal sorte que le chien a suffisamment de portée disposé sur celui-ci pour solliciter le porte-culas- pour passer par-dessus un arrêt de dernier se (111) dans une position avancée ; 50 coup de feu alors que le chien se déplace un poids anti-rebond au moins partiellement de la position reculée à la position avancée, contenu au sein du guide de ressort (8352) ; dans laquelle la liaison, pas le chien, a des une culasse portée par le porte-culasse (111) ; crans actionnés par un mouvement de dé- un extracteur attaché à la culasse ; tente. deux ressorts disposés au sein de la culasse 55 pour solliciter l’extracteur vers une position fer- 14. Anne à feu selon l’une quelconque des revendica- mée de l’extracteur (9100) ; tions 1, 7 ou 13, dans laquelle la tige transversale une barre inhibant la séparation du récepteur passe à travers les deux côtés d’une partie supé-

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rieure ouverte d’un étrier en forme de Y (7901) avec une partie inférieure qui passe sous le canon et sup- porte un ressort comprimé (7902) configuré pour pousser vers le haut sur le canon tout en tirant la tige transversale vers le bas serrée contre le canon 5 pour permettre au canon de se dilater en raison de la chaleur générée par un tir soutenu entièrement automatique pour permettre qu’un diamètre en dila- tation du canon dans la paire de vés (8081) se dé- place vers le bas pour comprimer davantage le res- 10 sort sans perturber une position ou une tenue de la cale basculante sur la tige transversale.

15. Arme à feu telle qu’elle est décrite dans l’une quel- conque des revendications précédentes, dans la- 15 quelle l’arme à feu est une arme à feu entièrement automatique.

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REFERENCES CITED IN THE DESCRIPTION

This list of references cited by the applicant is for the reader’s convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description

• EP 1479997 A1 [0007] • US 4475438 A, Leroy J. Sullivan [0198]

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