USOO8141289B2 (12) United States Patent (10) Patent No.: US 8,141,289 B2 Gomez et al. (45) Date of Patent: Mar. 27, 2012 (54) TOP OPENING, MODULAR TOP RAIL, 5,343,650 A 9, 1994 Swan MULTI-RIFILE ADAPTABLE FREE FLOAT A 8.28 3A, RAIL ADAPTORSYSTEM (ARM-R) 6.792,711 B2 92004 Battaglia 6,945,154 B1* 9/2005 Luth. .............................. 89.14.1 (75) Inventors: Jesus S. Gomez, Cambridge, MD (US); 7,216.451 B1* 5/2007 Troy ... ... 42.72 Darren Mellors, Fredericksburg, VA 7,707,762 B1* 5/2010 Swan .......... ... 42.85 (US) 7,716,865 B2 * 5/2010 Daniel et al. 42.75.02 2004/0049964 A1 3/2004 Vais ................... 42.75.02 (73) Assignee: LWRC International, LLC, 39883. A:ck 339. Sheet al. r. 1259, Cambridge, MD (US) k cited. by examiner (*) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 Primary Examiner — Bret Hayes U.S.C. 154(b) by 643 days. Assistant Examiner — Reginald Tillman, Jr. (74) Attorney, Agent, or Firm — Jacobson Holman PLLC (21) Appl. No.: 12/217,874 (57) ABSTRACT (22) Filed: Jul. 9, 2008 An improved Rail Adaptor System/Rail Accessory System O O RAS) which attaches to a firearm. The rail is top opening, (65) Prior Publication Data R and free floats the barrel. Provided is a R E. US 2012/OO42557 A1 Feb. 23, 2012 weight, strong platform for mounting firearm accessories. Heat transmission from the barrel assembly to the user is (51) Int. Cl. limited. The user is also protected from ventilated gases origi F4IGI/I6 (2006.01) nating from the operating system. A quick detachable top rail (52) U.S. Cl. ........................................................... 42/90 section is provided so that that gas system may be easily (58) Field of Classification Search ................ 42/90, 72, accessed. This removable top section of the rail is what makes 42/124, 71.01, 85, 75.01, 96, 75.02, 143, this device unique because the RAS may be installed without 42/115; 89/1.42 removing the barrel, gas system, front sight base, flash hider See application file for complete search history. or the barrel nut. The herein described RAS is adaptable to a wide variety of firearms with the use of conversion parts. The (56) References Cited top rail “returns to Zero' on reinstallation allowing the remounting of various optics and electronic gun sites without U.S. PATENT DOCUMENTS the need to realign them. 4,663,875 A * 5/1987 Tatro ............................ 42.71.01 5, 198,600 A 3, 1993 ENama 10 Claims, 7 Drawing Sheets U.S. Patent Mar. 27, 2012 Sheet 1 of 7 US 8,141,289 B2 FIGURE I U.S. Patent Mar. 27, 2012 Sheet 2 of 7 US 8,141,289 B2 er s U.S. Patent Mar. 27, 2012 Sheet 3 of 7 US 8,141,289 B2 U.S. Patent Mar. 27, 2012 Sheet 4 of 7 US 8,141,289 B2 U.S. Patent Mar. 27, 2012 Sheet 5 Of 7 US 8,141,289 B2 : U.S. Patent Mar. 27, 2012 Sheet 6 of 7 US 8,141,289 B2 U.S. Patent Mar. 27, 2012 Sheet 7 Of 7 US 8,141,289 B2 US 8,141,289 B2 1. 2 TOP OPENING, MODULAR TOP RAIL, 1. Lack of an ability to utilize existing free float rails, and MULTI-RIFILE ADAPTABLE FREE FLOAT tubes. If a traditional free float tube or rail were utilized RAIL ADAPTORSYSTEM (ARM-R) it would prevent the users from accessing the gas oper ating system above the barrel for cleaning purposes. BACKGROUND OF THE INVENTION Free float tubes and rails are necessary to prevent pres Sure from bi-pods and other accessories from pushing 1. Field of Invention the hand guard, tube or rail into contact with the barrel This invention relates to the field of firearms, specifically thus compromising the weapon's accuracy potential. accessories and mounting devices for firearms. 2. Also recognized is the inability of the user to mount 10 accessories which would traditionally be attached to rail 2. Prior Art interface systems. A rail interface system traditionally Several years ago the military started the SCAR program to consists of a closed tube securedator near the receiver of select a weapon which would replace all rifles currently uti the firearm with a variety of accessory mounting rails lizing a direct impingement operating system in use by the located about the periphery of the tube. Currently avail military. In short, a replacement of the M16/M4 rifle was 15 able rails do not interface with a gas system and/or do not being sought. allow for access to the operating system for mainte To explain the difference in the two systems, both direct gas aCC. impingement rifles and piston driven rifles have a hole toward 3. Other rails currently available do not facilitate the user's the front end of the barrel. As the cartridge is fired, burning access to the gas piston operating system for cleaning propellant causes the bullet to move down the bore of the rifle. without the total removal of the free float device. The propellant burns, generating expanding gases thereby Removal of the free floating rail in its entirety to clean increasing the pressure behind the bullet. As the bullet passes the operating system of the weapon will resultina loss of the hole in the barrel, some of the gas is tapped off. This is Zero, or the ability of the weapon to direct a discharged where the direct gas impingement and piston driven rifles bullet to a desired location would be compromised. In become different. 25 effect a military user would be prohibited from cleaning In a direct impingement rifle the gas is directed by means of his/her weapon while in a combat environment. along tube back into the receiver of the rifle. There is a cupped 4. Many currently available rail adaptor systems are diffi bolt carrier key which the tube fits into. The force of the gas cult to install requiring an armorer or gunsmith with pushes back the bolt carrier and reciprocates the rifle's self special tools to do the work. loading action. The disadvantage of this is dirty gases and 30 Previous rail adaptor systems (RAS’s) such as shown in carbon residues are deposited into the rifle's action and with U.S. Pat. No. 5,826,363 (Douglas Olson) have consisted of an sustained fire can lead to eventual failure as the close toler aluminum tube which replaces the hand guards. The tube has ance parts are caked with carbon. The long trip the gas must a series of standard 1913 Picatinny slotted rails at the 3, 6, 9, make before imparting its force also allows much of the gas to and 12 o'clock positions along the longitudinal axis of the leak out of the system if parts are not mated exactly. 35 bore. These Picatinny slotted rails allow for the use and align Rifles and carbines utilizing a gas piston system offer the ment of various accessories with the axis of the bore, an user a more reliable, robust, controllable, cleaner operating example being sighting equipment to increase the functional system. As the gas is tapped off the barrel, it is immediately ability of the host firearm. The RAS allows the end user to met by a gas piston. The gas drives the piston back which customize the firearm for a mission or make employment of pushes arod that actuates the action of the rifle. The gas piston 40 the rifle more ergonomic, effective and/or comfortable. A uses all of the tapped gas to generate the rear momentum of variety of RAS systems have been developed, predominantly the piston. Once it has moved back far enough with enough for M16/M4 rifles and clones thereof. While not the first, U.S. momentum to actuate the mechanism of the rifle, all excess Pat. No. 5,826,363 (Douglas Olson) is the first truly useful gases are rapidly vented off. The rapid venting of all excess RAS system in that it is capable of mounting and carrying the gases makes for an efficient and clean, self regulating system 45 modern load of combat accessories. since about 5% of the volume of gas is actually used to operate Examination of the prior art puts these systems into differ the firearm. None of the hot, dirty gas or carbon enters the ent categories. There are “conventional designs that work moving parts located in the receiver of the host firearm. with the standard handguard retaining ring on the rifle (delta In recent years there has been industry-wide interest to ring) and simply replace the hand guards. These systems are incorporate a gas piston system into the M16/M4 type rifle 50 usually found to be two-piece designs, two semi-circular and its variants. The push for this substantial change is due to halves making up a tube. These designs transmit the weight of the shortcomings which the direct gas impingement M16/M4 the accessories to the barrel of the rifle, changing the point of type rifle has shown in Sandy environments and after pro impact of the bullet. They also transmit external forces such longed use. as pressure from the users hand, or force exerted by the Traditionally the M16/M4 type rifle utilized a gas tube, 55 weight of the rifle resting on a fixed Support like a sandbag or well known in the prior art, which has a curve along its length bi-pod.