US00537.9677A United States Patent (19) 11 Patent Number: 5,379,677 Ealovega et al. 45) Date of Patent: Jan. 10, 1995 54 FIRE RATE CONTROL SYSTEM FOR A 56) References Cited SUBMACHINE GUN OR LIGHT MACHINE GUN U.S. PATENT DOCUMENTS 439,248 10/1890 Maxim .............................. 89/129.01 579,401 3/1897 Maxim ................................... 89/130 75) Inventors: George D. Ealovega, Kennebunk, 643,118 2/1900 Garland............................ 89/129.01 Me...; Richard P. West, Hatfield, 1,511,262 10/1924 Browning .. ... 89/130 England 1,573,655 2/1926 Sutter .................................... 89/130 1,895,719 1/1933 Lahti...... ... 89/129.01 73 Assignee: Bushman Limited, St. Albans, 2,035,303 3/1936 Delacre. ... 89/129.01 England 2,182,907 12/1939 Vollmer ................................ 89/130 2,748,661 6/1956 Simpson ................................ 89/130 2,995,988 8/1961 Reed .......... ... 89/129.0 21) Appl. No.: 227,572 3,650,177 3/1972 Huppet al. ........................... 89/130 3,650,177 10/1982 Swieskowski......................... 89/130 22 Filed: Apr. 14, 1994 FOREIGN PATENT DOCUMENTS 637802 5/1928 France .................................. 89/130 Related U.S. Application Data 133980 10/1919 United Kingdom ............. 89/129.01 63 Continuation of Ser. No. 906,882, Jul. 2, 1992, aban Primary Examiner-Stephen C. Bentley doned. Attorney, Agent, or Firm-Jones, Tullar & Cooper 57 ABSTRACT 30 Foreign Application Priority Data A fire rate control mechanism which allows an open May 12, 1992 GB United Kingdom ................. 9210300 bolt or closed bolt S.M.G. or L.M.G. to be, upon firing, momentarily arrested in a cocked condition and then to 51) Int. Cl. .............................................. F41A 19/04 be released to fire another round after a predetermined 52 U.S.C. ..................................................... 89/130 and preset lapse of time. 58) Field of Search..................... 89/129.01, 130, 140, 89/198 1 Claim, 6 Drawing Sheets 6 24 4, 8 1A S Y42-4ACN dan. 10, 1995 Sheet 2 of 6 5,379,677 U.S. Patent Jan. 5,379,677 Off; EZEZEITLFFFFFFF U.S. Patent Jan. 10, 1995 Sheet 4 of 6 5,379,677 ]WTVFZITTWIWITV EZEFEIÐIL-FFR Ø JDA? U.S. Patent Jan. 10, 1995 Sheet 5 of 6 5,379,677 zºE-TITE-T-V-V-U-S-V 22 No. U.S. Patent Jan. 10, 1995 Sheet 6 of 6 5,379,677 5,379,677 1. 2 automatic mode or in an automatic mode with a prede FIRE RATE CONTROL SYSTEM FOR A termined rate of fire. SUBMACHINE GUN OR LIGHT MACHINE GUN It is another object of the present invention to pro vide a fire-rate control mechanism which is simple in This application is a continuation-in-part, of applica 5 design, comprised of a minimum of parts, thus ensuring tion Ser. No. 07/906,882, filed Jul. 2, 1992, now aban reliability of the mechanism. doned. It is another object of the present invention to pro vide a fire-rate control mechanism which provides a FIELD OF THE INVENTION weapon which combines the simplicity and safety of an The present invention is directed generally to a fire O open-bolt system, with the first shot accuracy of a rate control system for an automatic weapon. More closed bolt system. particularly the present invention is directed to a fire It is another object of the present invention to pro rate control system in which the weapons cycle of fire vide a fire-rate control mechanism which is both light is interrupted for a preset and predetermined period of weight and compact enough to be positioned in the time. Most specifically, the present invention is directed 15 pistol grip of a weapon, thus not interfering with the to the use of a sear to stop the motion of the weapons position of the main spring or main spring guide rod or breech-block and the use of a hydraulic piston cylinder rear breech bolt buffer of the weapon. assembly as a release unit to control the sear's subse It is another object of the present invention to pro quent release of the breech-block. vide a fire rate control mechanism in which the fire rate DESCRIPTION OF THE PRIOR ART 20 control piston can be stored separate from the weapon A phenomenon known as "climb' or “stitching' is and which can be issued and installed only when re common to most S.M.G.'s in use today. Climb is caused quired, allowing the weapons automatic fire to be dis by an excessive rate of fire. For example, when fired on abled, but still allowing personnel to train with the same full automatic, a weapon typically does not have suffi 25 weapon in a semiautomatic mode. This is also important cient time to return to its original point of aim before with regard to security, since the rate control piston can each successive round is fired. The general result is one be located separate from the weapon during storage or round on target and thereafter a string of uncontrolled transport. shots moving upwards and off target. Such a lack of The present invention is a fire rate control mechanism control of shot placement is obviously both dangerous 30 which allows an open bolt or closed bolt S.M.G. or and very undesirable. L.M.G. (light machine gun) to be, upon firing, momen As the requirements of the military and law enforce tarily arrested in a cocked condition and then to be ment called for lighter and more concealable weapons, released to fire another round after a predetermined and the laws of physics ensured that with decreased weights preset lapse of time. came increased rates of fire and therefore increased 35 The mechanism to be described is shown as an alter rates of climb. Current S.M.G.'s (submachine guns) native to the electronic rate control system employed in have rates of fire which vary from approximately 600 the BUSHMAN I.D.W. 9 mm S.M.G. and was devel R.P.M. to over 2,000 R.P.M. oped in parallel so as to share as many components as Testing has shown, however, that in S.M.G.'s weigh possible between the two versions. A comparison of the ing somewhere between 4.5 and 8 pounds, the phenom two versions would show that except for the rate con enon of climb does not disappear until the rate of fire is trol units themselves, the majority of the remaining brought down below 450 R.P.M. (approximately). parts are interchangeable between the two models. The This can be demonstrated by the current model of the advantage of the new system lies in its simplicity and the BUSHMAN I.D.W. - 9 mm S.M.G. which employs an reduction of moving parts in the trigger mechanism. electronic rate control system set at 420 R.P.M. The 45 weapon weighs 5.7 pounds and does not climb when BRIEF DESCRIPTION OF THE DRAWINGS fired on full auto, even when fired by untrained person The foregoing, and additional objects, features and nel. In addition, prior art methods of fire rate control advantages of the present invention will become appar are limited in that a particular weapons rate of fire will ent to those of skill in the art from the following de vary depending on the particular cartridge load used in 50 tailed description of the preferred embodiment thereof, the weapon. Such an unpredictable rate of fire is unde taken in conjunction with the accompanying drawings, sirable. in which: FIG's. 1-6 are schematic illustrations of the present OBJECTS AND SUMMARY OF THE invention at various points in the cycle of operation of INVENTION 55 a weapon, in which, It is an object of the present invention to provide a FIG. 1 is a cutaway view of the weapon in a cocked fire-rate control mechanism which can eliminate position; weapon climb by limiting the firing rate to approxi FIG. 2 is a cutaway view of the weapon at a point mately 450 rpm or to whatever rate is determined, in immediately after the trigger has been pulled; practice, to eliminate climb for any particular individual FIG. 3 is a cutaway view of the weapon at the actual weapon model. point of firing; It is another object of the present invention to pro FIG. 4 is a cutaway view of the weapon at a point just vide a fire rate control mechanism which allows a sol after firing; dier in the field to alter a weapon's automatic rate offire FIG. 5 is a cutaway view of the weapon at a point at by removing and replacing a rate control piston, or to 65. which the weapons cycle of fire has been momentarily simply replace a defective unit, without the use of tools. arrested; and It is another object of the present invention to pro FIG. 6 is a cutaway view of the weapon immediately vide a weapon which can function in either a semi after having been released from an arrested state. 5,379,677 3 4. 10 is free to come up and is ready to engage the bolt 16 DETAILED DESCRIPTION OF THE at bent 18 at the moment the secondary-sear 26 has PREFERRED EMBODIMENT: disengaged from bent 36. The condition is again as In the drawings and in the description that follows, depicted in FIG. 1. The weapon is now recocked and like reference numerals refer to like elements. ready to be fired via another pull on trigger 22. The Figures depict the present invention in an auto Turning to a description of the weapons cycle of fire matic weapon, and illustrate the weapon at various during regulated full automatic fire, the cam-hammer 40 times in the weapons cycle of fire.