FIREARM

TECHNICAL FIELD

[0001] The present invention relates to the field of firearms and more particularly relates to a new rifle platform with enhanced utility innovative components and increased modularity.

BACKGROUND

[0002] Prior firearms have been, as a whole, adequate for their purposes. However, the advent of improved technologies in other fields, combined with the demands of current military tactics, both offensive and defensive, have created a need for a firearm that improves upon the current designs in the art. Practically speaking, the need has arisen for a lighter and more efficient weapon; one that is highly reliable, easily maintained, simple to operate and assemble, and easily enhanced as need requires.

[0003] The present invention is a firearm with numerous improvements that make it more reliable and simpler to operate and maintain as compared to the prior art. Its design also allows for easy modification, both in providing parts for modification and in the addition of such parts to the weapon.

[0004] A magazine release is a critical control that locks and releases the ammunition magazine from a firearm. Many firearms utilize a magazine that is linearly inserted into a magazine well in the firearm. For a number of reasons, including but not limited to the relatively long left and right sidewalls of the magazine, such firearms typically provide a side-locking recess on the magazine which is configured to engage with a magazine release mechanism of the firearm. This structure allows for a full, lateral push-button mechanism to lock and release magazines having a side-locking recess. For example, such a mechanism is used on the AR-15/M16 firearms and their associated M16 STANAG pattern magazine. Operating the side button slides the magazine release mechanism out of engagement with the side-locking recess in the magazine. This allows the magazine to drop free. However, standard AR- 15/Ml 6 firearms and other known firearms using magazines with side-locking recesses do not have a truly ambidextrous magazine release allowing actuation of the magazine mechanism by essentially the same user movement when the firearm is fired using either the left or right hand of a user.

[0005] Known firearms such as the Springfield XD and other newer generation pistols incorporate a magazine locking mechanism engaging a locking recess on the front of the magazine facilitating truly ambidextrous magazine release controls. Such structures greatly simplify the method of actuation. However, most existing systems, most notably the AR- 15/Ml 6 firearms cannot easily be converted to this method of operation. Literally millions of magazines having side-locking recesses for use with these firearms are in circulation and have been in use for many years. Thus, there is a significant logistical need for governments using the AR- 15/Ml 6 firearms and the associated Ml 6 STANAG pattern magazines to retain the use of the M16 STANAG pattern magazines. [0006] There have been attempts to provide an ambidextrous magazine release for firearms using a side-locking magazine by incorporating a lever into the magazine release. One such unit is known as the Norgon AmbiCatch™ and it is described in U.S. Patent No. 5,519,954. The Norgon AmbiCatch™ incorporates a lever into the magazine release and thus combines a translational magazine release actuation from one side of the firearm and a rotational magazine release action from the other side of the firearm in order to release the magazine. More particularly, the right side control functions using a translational movement which is the conventional movement used with the AR- 15/Ml 6 firearm magazine release, but the left side control uses a rotational actuation of the lever that has significantly less travel and may be more prone to accidental disengagement. Furthermore, the different modes of actuation complicate user training as different magazine release techniques have to be taught to users who fire the firearms using their right hand versus those firing the firearm using their left hand. This also creates potential for confusion and loss of critical time if users have to switch firing hands in the field while accounting for a different release mechanism in critical firing situations.

[0007] A somewhat better design which more closely approaches a truly ambidextrous magazine release is described in Smith, U.S. Patent No. 4,521,985. This catch release is intended for use with Colt ^® M1911 pistols. The Smith catch release solves at least some of the problems of the Norgon AmbiCatch™ structure by providing for actuation from both the left and right sides of the firearm by means of translational buttons. However, the Smith structure requires numerous parts and the different operational modes as between actuation from the left side and the right side may provide a different feel to the user. The Smith magazine release mechanism also requires a number of small, delicate parts, which may be detrimental to the durability and operation of the critical magazine release mechanism in dirty environments.

[0008] An ambidextrous push-button magazine release disclosed and claimed herein is intended to overcome one or more of the problems discussed above. [0009] Historically, firearm butt stocks have been made in a non-adjustable fixed configuration. Butt stock height can be important because an accurate marksman typically rests his face against the comb or top of the stock, which is also known as the cheek rest. In most instances where the standard firearm sights are fixedly attached to the firearm barrel, non-adjusting stocks do not present a serious problem. However, with the advent and prevalence of telescopic optical sights which ride above the standard firearm sights and standard government issue military firearms taking on broader missions from urban warfare to sniper attacks, greater versatility in the height of the cheek rest is necessary. [0010] By way of illustration, adjusting the cheek rest height typically has been considered necessary only for precision-sniper weapons. The extensive use of telescopic sights on these platforms makes eye alignment with these sighting devices of paramount importance. Looseness between the operator's head and the stock can cause misalignment between the eye and the stock and the scope. Issues such as maintaining proper eye relief and parallax are also effected. These scopes are often mounted too high above the stock for a user's cheek to gain a steadying purchase on the cheek rest. These effects all combine to potentially reduce firing accuracy.

[0011] For target applications and most military sniper applications, a high level of precision in position of a cheek rest is highly desirable. Thus, most firearm butt stocks having an adjustable cheek piece have relatively complex mechanisms requiring numerous components. The net effect is this often makes the stocks heavier, more difficult to assemble and more expensive to produce. Furthermore, these mechanisms are more prone to interference by dirt and grit encountered in military field applications. This is especially true with regard to government standard issue firearms which, as discussed above, are adaptable to numerous applications from use as sniper weapons to automatic weapons in relatively close combat.

[0012] The adjustable cheek piece for a firearm butt stock disclosed and claimed herein is intended to provide a simple, reliable and inexpensive solution to one or more of the problems discussed above.

[0013] A further need in the art is a quick change barrel system. Quickly changeable barrel systems are well known in the field of crew-served weapons such as machine-guns. These weapons are primarily belt-fed, fully-automatic, operate with an open-bolt mechanism and are intended to be used in roles requiring maximum firepower. Due to the quantity and

rate of fire, these weapons generate a significant amount of heat, primarily in the barrel and gas operating system (if one is present). The temperatures generated significantly affect weapon function by burning off lubricating oils, altering critical tolerances as parts expand at differential rates (depending on material), and temporarily and/or permanently weakening structural materials. This may cause various malfunctions including critical weapon failure (feeding & extraction failures, blown barrels, bolt failure etc.). To avoid these affects, cooling systems such as fins, fluting, increased forced air convection and water cooling have been employed historically. However, these systems can have various drawbacks including low effectiveness, weight, bulk, complexity and cost. Because of this, modern machine-guns such as the US M60 GPMG, FN MAG / M240 GPMG, and M2HB-QCB all utilize quick- change barrel (QCB) systems to completely replace a hot barrel with a fresh one. [0014] Rifles are not expected to generate the heat levels seen on machine-guns.

Therefore rifle barrels have traditionally been considered an integral part of the firearm. Barrels were never intended to be readily removed especially at the operator level. While this approach has worked historically, this type of design has imposed a number of limitations on these systems. With increased detachable box magazine capacity, lighter ammunition and the demands of high-end users such as special forces operators, rifles are experiencing heat issues similar to machine-guns. QCB systems allow similar barrel swaps to prolong weapon use under intense operational circumstances.

[0015] These limits have given rise to rifle systems and modifications designed to allow users to change the barrel. Systems such as the LMT Monolithic Rail Platform (MRP) and FN SCAR attach the barrel with a number of screws requiring additional tooling in order to operate. Other systems are true QCB systems such as the Leitner-Wise Modular Weapon System (MWS) and MGI Hydra that incorporate two-point lateral lever or cam systems which mount the barrel and allow quick change ability without tools. The benefits of such systems are numerous and include mission adaptability, easier serviceability, easier caliber change of the weapon, and more compact storage.

[0016] Disclosed and claimed is an improved QCB system with numerous improvements that make it simpler to operate and maintain as compared to the prior art.

SUMMARY OF THE INVENTION

[0017] In view of the foregoing disadvantages inherent in the known types of firearms, this invention provides an improved firearm with increased utility. As such, the

present invention's general purpose is to provide a new and improved firearm that is more reliable, more efficient to operate and maintain, presents greater utility in its basic embodiment and is easily enhanced.

[0018] To accomplish these objectives, the firearm comprises four major components, the upper receiver, the grip housing the stock and the barrel. Operable parts are contained within the upper receiver and the grip housing, which are hingedly attached for easy access to said operable parts. The grip housing contains the trigger assembly, a bolt catch, hammer and sear. It also presents the magazine well and structure and a safety structure. The upper receiver contains the bolt assembly, a short stroke gas piston system with improved functionality, recoil system, a novel charging assembly, mounting structure for the barrel and the firing chamber. The stock, which does not contain recoil components, is attached to both the upper receiver and the grip housing and further comprises a three dimensionally adjustable cheek riser. The barrel and mounting assembly features a novel quick release changing system.

[0019] Ambidextrous Magazine Release

[0020] An ambidextrous magazine release for a firearm is provided for a firearm having a magazine well configured to operatively receive a magazine having a side-locking recess. The ambidextrous magazine release comprises a linkage moveable between an engaged position and a disengaged position having a lock pin configured to be received in a side-locking recess of a magazine operatively received in the magazine well with the linkage in the engaged position and to clear the side-locking recess with the linkage in the disengaged position. An actuator is provided on the firearm comprising a bar having opposing push surfaces extending between a right and left side of the firearm. An interface is provided between the linkage and actuator with the interface being configured so that as either of the opposing push surfaces of the bar is pushed by a user, the linkage is moved between the engaged and the disengaged position.

[0021] In one embodiment, the linkage interface is configured so that as either of the opposing push surfaces is pushed by a user, the feel to the user is essentially the same. In another embodiment, biasing means are provided for biasing the linkage in the engaged position. Such an embodiment further includes the linkage interface being a recess in the bar defining a pair of converging cam surfaces and a cam rider extending from the linkage into contact with the cam surfaces, the linkage being in the engaged position with the cam rider at the convergence of the cam surfaces. In such an embodiment, the biasing means biases the cam rider into the convergence of the cam surfaces. An embodiment may include the linkage

being L-shaped, with the lock pin extending inward from one leg of the L and the cam rider extending outward from the other leg of the L. In such an embodiment a pivotal connection is provided between the firearm and the L-shaped linkage at the intersection of the legs of the L. Such an embodiment may further comprise the leg of the L having the cam rider residing juxtaposed to the actuator bar with one cam surface distal of the cam rider and the other cam surface proximal of the cam rider with the cam rider at the convergence of the cam surfaces. The respective inclines of the cam surfaces may be different. In one embodiment the proximal cam surface has a steeper incline than the distal cam surface. The respective inclines may be selected to provide essentially the same feel to a user when pushing the actuator from either of the left or right side of the firearm.

[0022] The ambidextrous push-button magazine release for side-locking ammunition magazines disclose herein is truly ambidextrous since the same motion and feel is experienced by a user disengaging the magazine from either the left or right side of the firearm. Furthermore, the length of travel is similar whether actuated from the left or right side. The ambidextrous push-button magazine release for side-locking ammunition magazines includes only four simple parts and thus is inexpensive to build, easily assembled, simple to operate and not prone to interference from grit and shock when used in the field. Further advantages will be apparent from review of the Detailed Description and appended claims.

[0023] Adjustable Cheek Piece

[0024] A firearm butt stock with an adjustable cheek piece comprises an elongate stock base having a top, a bottom, a right side, a left side, a proximal end and a distal end. The stock base has a transverse pivot shaft near the stock base top and a transverse catch shaft spaced from the pivot shaft lengthwise of the stock base near the stock base top. A cheek piece has a proximal end and a distal end and a left and a right sidewall. The cheek piece defines a plurality of lengthwise stacked receptacles opening toward a proximal end of the cheek piece and an elongate hole having a distal and a proximal end spaced lengthwise and distal of the stacked receptacles. The stacked receptacles, the catch shaft, the elongate hole and the pivot shaft are configured so that with the pivot shaft received in the elongate hole and the pivot shaft at the distal end of the elongate hole, the catch shaft is received in one of the stacked receptacles and the cheek piece is prevented from pivoting about the pivot shaft. With the pivot shaft at the proximal end of the elongate hole, the catch shaft clears the opening of the stacked receptacles and the cheek piece can pivot about the pivot shaft. A spring detent is provided in operative association with one of the pivot shaft and the catch

shaft. The spring detent prevents relative movement of the pivot shaft and the proximal and distal ends of the elongate hole without application of a lengthwise force to the cheek piece in a desired lengthwise direction of movement sufficient to overcome the spring detent. [0025] In one embodiment the spring detent comprises the elongate hole being peanut-shaped with a proximal lobe and a distal lobe separated by a waist, the waist having a width less than a diameter of the pivot shaft, and at least one of the cheek piece and the pivot shaft being formed of a resilient material. In such an embodiment the cheek piece may have a pair of peanut-shaped holes axially aligned in the left and right sidewalls and the elongate base may have a pair of pivot shafts axially aligned and extending from the right side and the left side of the stock base near the stock base top, with the left and right pivot shafts being received in the left and right peanut-shaped holes, respectively. Such an embodiment may further include the cheek piece sidewalls defining opposing lengthwise slots in an inner surface forming the plurality of lengthwise stacked receptacles and the elongate base includes a pair of catch shafts axially aligned and extending from the right side and the left side of the a stock base near the stock base top receivable in the lengthwise receptacles. The cheek piece and the pivot shafts may be formed of the same resilient material. The resilient material may be a resilient polymer and the cheek piece as well as the elongate stock base may be integrally formed from the resilient polymer.

[0026] Another aspect is a firearm comprising an upper receiver, a grip housing, a barrel, and a butt stock including an adjustable cheek piece in the various embodiments as described above.

[0027] Quick Change Barrel Release

[0028] An improved quick change barrel system with increased utility, intuitive use and rapid deployment is disclosed. As such, its general purpose is to provide a new and improved quick change barrel system that is more efficient to operate and maintain, and presents an intuitive interface for users.

[0029] The quick change barrel system comprises a barrel which is mounted in a cantilevered manner. The rear of the barrel slides and mounts into a barrel trunnion and is subsequently locked into place with a barrel lock ring via an interrupted, non-continuous thread that mates with the barrel trunnion. A folding wire handle is provided to assist in applying leverage to turn the barrel lock ring thereby applying pressure to the barrel extension flange and providing a sealed joint. A spring-loaded detent (barrel lock plunger) locks into grooves on the barrel lock ring to prevent it from working loose.

[0030] Changing Handle With Forward Assist

[0031] A charging system comprises a charging actuator, upon which additional components reside, a charging blade with two charging knobs for user interface, a spring loaded forward assist lever to selectively engage the bolt carrier, and a detent spring to interface with firearm geometry and keep the actuator in a stowed position when not in use. [0032] The charging handle for a firearm with a forward assist function allows for the user to have full control of the bolt carrier group in order to feed cartridges and push the bolt into battery if an obstruction or additional force is required. This can occur due to debris, fouling, a weakened action spring or magazines which require additional feeding force. Numerous improvements to the present invention make it simpler to operate and maintain as compared to the prior art. Specifically, the forward assist function given by the present invention is actionable along the entire length of the bolt carrier's path of travel and requires no special motions from the user, unlike forward assists used in the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Fig. 1 is a left plan view of the firearm according to the present invention;

[0034] Fig. 2 is a cross-sectional view of the firearm of Fig. 1 ;

[0035] Fig. 3 is a left plan view of the upper and lower receivers demonstrating their hinged relationship;

[0036] Fig. 4 is the receiver components of Fig. 3, with a contained magazine;

[0037] Fig. 5 is a left plan view of the barrel assembly of the present invention;

[0038] Fig. 6 is a perspective view of the barrel assembly of Fig. 5;

[0039] Fig. 7 is a left side elevation view of the lock ring and trunnion of the present invention, assembled;

[0040] Fig. 8 is a left side elevation view of the trunnion of the present invention;

[0041] Fig. 9 is a perspective view of the lock ring and trunnion of Fig. 7;

[0042] Fig. 10 is a cross-sectional view of the lock ring and trunnion of Fig. 9;

[0043] Fig. 11 is a perspective view of the barrel assembly and gas piston systems;

[0044] Fig. 12 is a cross-sectional view of the systems of Fig. 11;

[0045] Fig. 13 is a close-up view taken in circle 13 of Fig. 12;

[0046] Fig. 14 is a perspective view of the gas piston system's gas regulator;

[0047] Fig. 15 is another perspective view of the gas regulator;

[0048] Fig. 16 is a perspective view of the gas piston;

[0049] Fig. 17 is a perspective view of the gas washer;

[0050] Fig. 18 is a left side elevation view of the barrel, gas system and charging assembly of the present invention;

[0051] Fig. 19 is a sectional view of the components of Fig. 18;

[0052] Fig. 20 is a close up view of the components taken in box 20 of Fig. 19;

[0053] Fig. 21 is a close-up view of the charging handle assembly engaged with the bolt carrier;

[0054] Fig. 22 is a top perspective view of the upper receiver;

[0055] Fig. 23 is a bottom perspective view of the upper receiver;

[0056] Fig. 24 is a left side elevation view of the upper mounting rail and front sight;

[0057] Fig. 25 is a side elevation view of the front sight of the present invention, with retaining structure;

[0058] Fig. 26 is a perspective view of the front sight assembly;

[0059] Fig. 27 is a left side elevation view of the lower receiver and the bolt assembly;

[0060] Fig. 28 is a left side elevation view of the bolt catch with the bolt assembly;

[0061] Fig. 29 is a perspective view of the lower receiver of the present invention with its contained components;

[0062] Fig. 30 is a perspective view of lower receiver components;

[0063] Fig. 31 is a left-side elevation view of a firearm grip housing with a linearly received side-locking ammunition magazine operatively received in a magazine well; [0064] Fig. 32 is a perspective view of the grip housing of Fig. 31 with the magazine and trigger mechanism removed and the magazine release mechanism exploded therefrom; [0065] Fig. 33 is a perspective view of the assembled ambidextrous magazine release mechanism;

[0066] Fig. 34 is a cross-sectional view of the assembled ambidextrous magazine release mechanism of Fig. 33 taken along line 4-4 of Fig. 33;

[0067] Fig. 35 is a cross-sectional view of the grip housing of Fig. 31 taken along line

5-5 of Fig. 31 with the trigger mechanism removed for clarity; [0068] Fig. 36 is a cross-sectional view of the ambidextrous magazine release mechanism in an engaged position as viewed in Fig. 35 with a magazine having a side- locking recess; [0069] Fig. 37 is the ambidextrous magazine release mechanism of Fig. 36 in a disengaged position when pushed from the right;

[0070] Fig. 38 illustrates the ambidextrous magazine release mechanism in a disengaged position when pushed from the left;

[0071] Fig. 39 is a perspective view of a grip housing and stock;

[0072] Fig. 40 is a left side elevation view of Fig. 39;

[0073] Fig. 41 is a left side elevation view of a fire arm incorporating the adjustable cheek piece for a firearm butt stock;

[0074] Fig. 42 is a left side elevation view of the butt stock of the firearm of Fig. 41 incorporating the adjustable cheek piece;

[0075] Fig. 43 is a top plan view of a cheek piece comprising the adjustable cheek piece for a firearm butt stock;

[0076] Fig. 44 is a cross-sectional view of the cheek piece of Fig. 43 taken along line

4-4 of Fig. 3;

[0077] Fig. 45 is a left side elevation view of an elongate stock base comprising the adjustable cheek piece for a firearm butt stock;

[0078] Fig. 46 is a top plan view of the stock base of Fig. 45 ;

[0079] Figs. 47A-47D are left side elevations views illustrating height adjustment of the adjustable cheek piece for a firearm butt stock;

[0080] Fig. 48 is a top side elevation view of the barrel assembly according to the present invention;

[0081] Fig. 49 is a left side elevation view of the barrel assembly of Fig. 48;

[0082] Fig. 50 is a sectional view of the barrel assembly of Fig. 48, taken along line

C-C;

[0083] Fig. 51 is a perspective view of the barrel assembly of Fig. 48 without the barrel trunnion;

[0084] Fig. 52 is a left side elevation view of the barrel assembly of Fig. 51 ;

[0085] Fig. 53 is a left side elevation view of the lock ring and trunnion of the present invention, assembled;

[0086] Fig. 54 is a perspective view of the lock ring and trunnion of Fig. 53;

[0087] Fig. 55 is a cross-sectional view of the lock ring and trunnion of Fig. 54;

[0088] Fig. 56 is a left plan view of the barrel trunnion of the present invention;

[0089] Fig. 57 is a perspective view of the barrel trunnion of Fig. 56;

[0090] Fig. 58 is a top plan view of the barrel trunnion of Fig. 56;

[0091] Fig. 59 is a sectional view of the barrel trunnion of Fig. 58, taken along line B-

B;

[0092] Figs 60A-60D are successive perspective views of the barrel assembly, depicting the disassembly of the present invention;

[0093] Fig. 61 is a left side elevation view of the firearm of Fig.1, partially disassembled;

[0094] Fig. 62 is a left side elevation view of the receiver and receiver stored components of the firearm of Fig. 1;

[0095] Fig. 63 is a left side elevation view of the receiver stored components of the firearm of Fig. 1;

[0096] Fig. 64A is a top plan view of the charging apparatus according to the present invention;

[0097] Fig. 64B a is a close-up left plan view taken between lines C-C in Fig. 64A;

[0098] Fig. 65 is a front elevation view of the charging apparatus of Fig. 64A;

[0099] Fig. 66 is a rear elevation view of the charging apparatus of Fig. 64A;

[00100] Fig. 67A is a perspective view of the apparatus of Fig. 64A;

[00101] Fig. 67B is a close up view taken in circle B of Fig. 67A;

[00102] Fig. 68 A is a left side elevation view of the charging apparatus and bolt carrier group of the firearm of Fig. 1, in non-reciprocal relationship;

[00103] Fig. 68B is a close-up view, taken in circle D of Fig. 68A;

[00104] Fig. 69 is a perspective view of the charging system and bolt carrier group of

Fig. 68A;

[00105] Fig. 7OA is a left side elevation view of the charging apparatus and bolt carrier group of the firearm of Fig. 1, in a reciprocal relationship;

[00106] Fig. 7OB is a close-up view, taken in circle E of Fig. 7OA;

[00107] Fig. 71 is a perspective view of the charging system and bolt carrier group of

Fig. 7OA;

[00108] Fig. 72 is an exploded view of the charging system of the present invention;

[00109] Fig. 73 is a left side elevation view of the charging system and it's mounting components, with the charging handle actuator removed;

[00110] Fig. 74A is a sectional view of the system of Fig. 73, taken along line A-A; and

[00111] Fig. 74B is a close-up view, taken in circle E of Fig. 74A.

DETAILED DESCRIPTION OF THE INVENTION

[00112] As used herein, the articles "a", "an" and "the", as used in this specification, include plural unless the content clearly dictates otherwise.

[00113] With reference to Fig. 1, a firearm 10 has four major components, namely the barrel 12, upper receiver 14, grip housing 16 and stock 18. Internal parts are generally located in the upper 14 receiver and the grip housing 16. Fig. 2 depicts a trigger control group 15 and a magazine 13 as residing in the grip housing 16 and a short stroke gas piston system 17 and charging system 19 in the upper receiver 14. The firing chamber 21 is also located in the upper receiver 14. The upper 14 receiver and the grip housing 16 are hingedly attached (Figs. 3 and 4). The connection hinge 20 is located to the fore end of the grip housing 16. It should also be noted that all of the magazine connection structure is located in the grip housing 16, so the receivers may be opened even when a magazine 13 of any kind is still inserted in the magazine well. It should be noted that some magazines are mountedly attached to the barrel trunnion (such as the AK magazine) and would lock the receivers together without alternate securing means.

[00114] The firearm 10 has a free floating barrel 12 which is cantileverally attached to the upper receiver 14, the barrel assembly is depicted in Figs. 5-10. In the present invention, barrel 12 is mounted upon a lock ring 22 which interfaces with the barrel trunnion 26. A wire handle 24 extends from the lock ring 22 to aid in assembly and disassembly of the barrel structure from the firearm. Trunnion 26 and lock ring 24 have an interrupted thread interface 28 and locking structure to hold them together. The preferred locking structure is a spring loaded detent pin 25 which interfaces with ridges 21 on the lock ring 22 to prevent rotation, thus keeping the lock ring 22 and trunnion 26 together. A particular embodiment of a quick change barrel system is described in greater detail below with reference to Figs. 48-60. [00115] The gas piston system 19 resides in the upper receiver and is depicted in Figs.

11-17. This system resides over the barrel 12 and is fastened to the barrel 12 via mounting structure 32. Gas from firing ammunition passes through a channel 31 in the mounting structure into a separate gas regulator 34. The regulator 34 is removable from the mounting structure 32 and may be positioned so that any one of six gas orifices 33 abut the channel 31. These orifices are of varying size so as to control gas passage into the system. Except for a single mounting screw, the adjustment is can be made without tools. The gas piston 36 generally resides within the regulator 34 until blown backwards by pressurized gasses. Gas collects in a forward chamber of the regulator, which is sealed off by a plug 39 located on the

front of the piston 36. Once pressurized, the gasses push the piston 36 and connected operation rod 38 backwards. The operation rod 38 then impinges upon the action of the weapon, allowing for semi-automatic and automatic firing. Control vents 35 lessen gas pressure greatly once piston 36 slides beyond them, and lessen stress on the system. Gas ring 37 is provided in groove 41 of the piston 36 to better seal the regulator 34 and piston 36 from excessive gas leakage. Control rod 38 is mounted upon the piston 36 at orifice 40. [00116] The charging handle system, shown in Figs. 18-21, is a hybrid design that is intended to be utilized mostly in the non-reciprocating role. The charging handle group consists of a charging handle block 46, charging handle blade 43, and charging handle latch 47. All the parts are effectively linked to each other when assembled except the charging handle latch 43 which may rotate. When stowed in the forward most position, the charging handle is non-reciprocating and the charging handle latch 43 is forced upward by mating geometry on the rear of the barrel trunnion 26. When pulled to the rear, the charging handle latch 47 is allowed to drop (under spring pressure) into engagement with the bolt carrier 42 at notch 45. This provides a two-way lock on the bolt carrier 42 and thus makes the charging handle capable of being used as a forward assist (Fig. 21). The current mechanism would then also cause the charging handle to reciprocate if fired until the charging handle is manually locked forward again. The blade 43 is reversible to be used on either the right or left-hand side of the weapon. A particular embodiment of a charging handle with a forward assist function is described below with reference to Figs. 61-74B.

[00117] It should be noted in Figs. 22, 23 that the upper receiver 14 is reinforced with two cross beams 49. This reinforcement helps to prevent splaying and separation of the upper receiver 14. The firearm also features an integral flip-up front sight 50 (Fig. 1) located on an upper rail attached to the upper receiver (Fig. 24). The integral flip front sight presents standard M 16 sight post 55 and is adjustable for elevation. Front sight post features a pistol- type front sight blade 54 that is visible in the stowed position. This is similar to the HK MP-7 submachine-gun which features sights that have a blade front and notch rear (pistol type) that fold out into a post and aperture (M16-type). The sight is a flip-up sight, with a detent 58 that stops the sight at post 56 (Figs. 25, 26).

[00118] The bolt catch control (Figs. 27, 28) is ambidextrous and located on the bottom- forward section of the trigger guard. It is intended to be manipulated with the index finger (trigger finger) and may be pushed up to lock the bolt group to the rear and pushed down to release it from a locked position. This is accomplished by taking the user input from the bolt release paddle 62 and transmitting it via the bolt stop 60 to the bolt 44 face.

[00119] The fire control group (Figs. 29, 30) is contained in a housing referred to as a trigger pack 64 and drops into the lower receiver 16. It uses standard AR-15/M16 fire control parts including the Hammer, Trigger, Disconnector and associated springs. The fire selector 66 utilizes the same drum portion as the AR- 15/Ml 6 but has an additional control lever. One lever is located on each side of the Lower Receiver and the selector thus ambidextrous. It should also be noted that the area 68 just fore of the magazine well is textured and structured to provide another gripping surface for the user.

[00120] Fig. 31 is a side elevation view of a grip housing 16 of a firearm incorporating an ambidextrous push-button magazine release for side-locking ammunition magazines in accordance with the present invention. Also illustrated in Fig. 31 is an ammunition magazine 13 linearly received in a magazine well 14 (see Fig. 2) of the grip housing 16. A ambidextrous magazine release mechanism 116 is viewed in part in Fig. 1 and its position relative to the trigger assembly 150 is readily apparent.

[00121] The ambidextrous magazine release mechanism 116 is shown exploded from the grip housing 16 in Fig. 32 with the magazine and a trigger assembly removed from the grip housing. The ambidextrous magazine release mechanism 116 consists of an actuator bar 118, a linkage 120, a pivot pin 122 and a torsional spring 124.

[00122] The ambidextrous magazine release mechanism 116 is shown assembled in a perspective view in Fig. 33 and in a cross-sectional plan view in Fig. 34. With reference to Figs. 33 and 34, the actuator bar 118 has left and right opposing push surfaces 126, 128, enlarged relative to the body of the actuator bar 118 for user comfort and accessibility. The push surfaces include texturing to minimize the risk of a users finger slipping off of the push surfaces. A recess 130 is formed in a leading surface of the actuator bar 118 near the right push surface 128. The recess 130 defines a pair of converging cam surfaces including a proximal cam surface 132 and a distal cam surface 134 meeting at a convergence 136. [00123] The linkage 120 has an L-shaped configuration that includes an inwardly protruding lock pin 138 at a distal end of one leg of the L and an outwardly protruding cam follower 140 at the distal end of the other leg of the L. The pivot pin 122 is received in a hole 142 at the intersection of the legs of the L. The torsional spring 124 is sized to be received in a cavity 144 at the intersection of the legs of the L with the coil of the torsional spring 124 receiving the pin 122. One end of the torsional spring 124 is received in a hole 146 communicating with the cavity 144 and the other end of the torsional spring 148 abuts a portion of the grip housing 110 as viewed in Fig. 35.

[00124] The ambidextrous magazine release mechanism 116 is shown installed in the grip housing 110 in Fig. 35. The actuation bar 118 is received in holes on the left and right side of the grip housing 110 in proximity to trigger 150, as best viewed in Fig. 31. The actuator bar extends between the left and right sides of the grip housing with the left and right surfaces 126, 128 readily accessible to the left and right index fingers of a user firing with his left hand or right hand, respectively. The linkage 120 is pivotally attached inside the grip housing 110 by means of the pin 122 and is positioned with the leg of L having the outwardly protruding cam follower 140 juxtaposed to the actuator bar 118 with the cam follower 140 received in the recess 130, for using an interface between the linkage and the actuator bar. The other leg of the L is dimensioned so that lock pin 138 is received in a hole 152 in the grip housing 110 which aligns with a side-locking recess 154 of an ammunition magazine 112 operatively received in the magazine well 114. As depicted in Fig. 35, the torsional spring 124 contacts an inner corner of the grip housing 110 and engages the linkage 120 to bias the lock pin 138 into engagement with the side-locking recess 154 of the ammunition magazine 112. At the same time the cam follower 140 is biased into contact with the cam surfaces of the recess 130 and rests in the convergence 136. This "engaged position" is illustrated in Fig. 36 with the grip housing and other components removed for the sake of clarity. When a user pushes the actuator bar 118 from the right, the cam follower 140 rides the distal cam surface 134, pivoting the linkage 120 to bring the lock pin 138 out of engagement with the side-lock recess 154. This is illustrated in Fig. 37. Fig.38 illustrates the lock pin 138 disengaged from the side-locking recess 154 when the actuator bar 118 is pushed from the left. [00125] Referring to Fig. 34, it can be observed that the distal cam surface 134 does not have as steep an incline as the proximal cam surface 132. These inclines are selected so that the "feel" to a user when pushing the actuator bar 118 to the left or to the right is essentially the same. As used herein, "feel" means the type of motion and amount of force applied to the actuator. Different inclines are required to provide essentially the same feel because when the actuator bar 118 is pushed to the left the cam follower 40 is essentially "pulled" up the proximal cam surface 132. This action requires relatively less force than required when the cam follower 140 is "pushed" up the distal cam surface 134 when the actuator bar 118 is pushed from the right. By providing a lesser incline on the distal cam surface the relative force can be substantially equalized to provide essentially the same feel with respect to the amount of force required in actuating the ambidextrous magazine release mechanism from either the right or the left. Obviously, in this design the amount of travel necessary to disengage the magazine pushing from the right is slightly greater than pushing

from the left, but this difference does not interfere with the ambidextrous use of the ambidextrous magazine release mechanism because the motions and feel are otherwise identical.

[00126] The stock unit 18 is modular and attaches to both the upper and grip housing

16, shown in Figs. 33 and 34. Various stock configurations are possible due to the modular design and lack of a rear protruding receiver extension (i.e. buffer tube). The disclosed stock is hinged 76 and is secured by latching mechanism 80. The folding stock design is also adjustable for length of pull and has two cheek- weld height positions with adjustable cheek riser 212, described in greater detail below. The stock may contain storage (as shown in Fig. 2) or other advantageous devices as there is no receiver extension tube. [00127] Fig. 4 is a side elevation view of a firearm 210 incorporating an adjustable cheek piece 212 on a firearm butt stock 214. In Fig. 42 the butt stock 214 with the adjustable cheek piece 212 is shown with the grip housing, upper receiver and barrel of the firearm 210 removed for the sake of clarity. The adjustable cheek piece 122 is comprised generally of a cheek piece 216 and an elongate stock base 218 upon which the cheek piece 216 rides. [00128] Fig. 43 is a top view of the cheek piece 216. Fig. 44 is a cross-section of the cheek piece 216 taken along line 4-4 of Fig. 43. The cheek piece 216 comprises a top 220, a left sidewall 222 and a right sidewall 224 which enclose a cavity 226. The sidewalls near the proximal ends 228 are textured as illustrated at 230 and at the distal end 232 the top 220 has a lengthwise slot 230. As used herein, proximal and distal refer to the location relative to the grip housing of the assembled firearm 210 illustrated in Fig. 41. [00129] Referring to Fig. 44, the cheek piece 216 defines a plurality of stacked receptacles 236 opening toward a proximal end of the cheek piece 216 near the proximal end of the cheek piece 216. The lengthwise stacked receptacles 236 consist of opposing lengthwise slots 238 which are axially aligned on an interior surface of the left and right sidewalls 222, 224. The opposing lengthwise slots 238 on an interior surface of the right sidewall are illustrated in Fig. 44 and mirror image opposing lengthwise slots 238 are provided in the inner surface of the left sidewall 222.

[00130] At the distal end of the cheek piece 216 is an elongate hole 240. More particularly, a pair of axially aligned elongate holes 240 are defined in the left and right sidewalls with the hole 240 in the right sidewall 224 being the only one shown in Fig. 44. The elongate hole 240 is peanut-shaped and comprises a proximal lobe 242 and a distal lobe 244 separated by a constricted waist 246. Referring to Fig. 44, the proximal lobe 242 and the distal lobe 244 are spaced along the length of the cheek piece 216.

[00131] Fig. 45 depicts an elongate stock base 218 having a proximal end 250, a distal end 252, a top 254, a bottom 256, a left side 258, and a right side 259. Near the top 254 at the distal end 252 of the stock base 218 is a transverse pivot shaft 260. Spaced lengthwise of the transverse pivot shaft 260 near the top 254 and the proximal end 250 of the stock base 218 is a transverse catch shaft 262. More particularly, referring to Fig. 46, in the present embodiment the transverse pivot shaft 260 comprises a pair of axially aligned pivot shafts 260A and 260B extending from the left and right sides of the stock base near the stock base top. Similarly, the transverse catch shaft 262 comprises a pair of axially aligned shafts 262A and 262B extending from the left and right side of the stock base 218, respectively. [00132] The pivot shafts 260A, 260B are sized to be received in the elongate hole 240 with the catch shaft 262 being receivable in the opposing lengthwise slots 238. More particularly, the transverse pivot shafts 260A, 260B, the transverse catch shafts 262 A, 262B, the elongate holes 240 and the opposing lengthwise slots 238 of the stacked receptacles 236 are configured so that with the pivot shaft received in the elongate hole and the pivot shaft at the distal end of the elongate hole, the catch shaft is received in one of the stacked receptacles 326 and the cheek piece 216 is prevented from pivoting about the pivot shaft 260. With the pivot shaft 260 at the proximal end of the elongate hole 240, the catch shaft 262 clears the opening of the stacked receptacles 236 and the cheek piece 216 can pivot about the pivot shaft to be brought into alignment with a select stacked receptacle 236. A spring detent 264 (see Fig. 42) is formed by a relationship between the transverse pivot shaft 260 and the peanut-shaped hole 240. More particularly, the peanut-shaped hole is sized so that the waist 246 has a width slightly less than an outer diameter of the pivot shaft 260. In the embodiment described in detail herein, both the cheek piece 216 and the elongate stock base 218, including the transverse pivot shaft and the transverse catch shaft are integrally formed from a resilient material. However, only one of the transverse pivot shaft and a portion of the cheek piece defining the peanut-shaped hole need be made of a resilient material. By virtue of the resiliency, proximal and distal lobes 242, 244 can be moved lengthwise relative to the transverse pivot shaft 260 by application of a lengthwise force to the cheek piece 216 in a desired lengthwise direction of movement sufficient to overcome the spring detent 264. [00133] The resilient material from which the cheek piece 216 and the elongate stock base (including the transverse pivot shaft 260A and 260B and transverse catch shaft 262A and 262B) are formed and can be any material with sufficient resiliency to provide the spring detent feature described above. In one embodiment the resilient material is a resilient polymer. Representative polymers include nylon, polypropylene, styrene and other synthetic

organic polymers. The resilient material may include glass fiber reinforced polymers and the polymers may include impact modifiers. The detent action should be sufficient to prevent inadvertent lengthwise movement of the cheek piece 216 relative to the elongate stock base 218. For example, the detent should be able to resist movement from firing recoil and normal handling and use of the firearm. In other words, it should typically move only under deliberate application of force by a user.

[00134] The specific configuration of the elongate slot 240, the stacked receptacles 236 of the cheek piece 216, the transverse pivot shaft 260A and 260B and transverse catch shaft 262A and 262B are best viewed with reference to Figs. 47A-47D. These figures illustrate the cheek piece in cross-section, generally as described in Fig. 44, though with various details omitted for clarity.

[00135] Fig. 47 A illustrates the cheek piece 216 in a lowered locked position. The pivot shaft 260 is received in the distal lobe 244 of the peanut-shaped hole 240 and the transverse catch shaft 262 is received in an upper stacked receptacle 236. In this position the cheek piece 216 is locked against lengthwise movement and is prevented from pivoting about the pivot shaft 260. In Fig. 47B the cheek piece 216 has been slid lengthwise in a distal direction to move the transverse pivot shaft 260 into the proximal lobe 242 of the peanut- shaped hole 240. In this position the cheek piece 216 can pivot about the pivot shaft 260 and, as illustrated in Fig. 47C, can be brought into alignment with the lower stacked receptacle to effectively raise the level of the cheek piece 216. With the cheek piece thus aligned, a proximal lengthwise force can be applied to the cheek piece 216 to move the distal lobe 244 into engagement with the pivot shaft thus locking the cheek piece in a raised position and preventing further pivoting of the cheek piece about the pivot shaft 260, as illustrated in Fig. 47D.

[00136] The embodiment described herein has two stacked receptacles 236. Any number of stacked receptacles could be provided for greater degree of variation and precision of variation of height of the cheek piece 216. In addition, in the embodiment described herein the transverse catch shaft 262A and 262B has a flattened as opposed to a round cross- section to provide greater surface area in contact with the portions of the cheek piece side wall defining the stacked receptacles 236.

[00137] The slot 234 at the distal end of the top 220 of the cavity 226 is provided to facilitate attachment of the cheek piece 216 to the elongate stock base 218. [00138] The adjustable cheek piece for a firearm butt stock can be reliably and inexpensively manufactured. For example, the cheek piece 216 and the stock base 218 may

be integrally formed by injection molding of a resilient polymer. In addition, the cheek piece can be readily assembled and disassembled. The disclosed embodiments also provide a highly simplified and reliable spring detent system for securing the adjustable cheek piece at a desired height.

[00139] The quick change barrel assembly is depicted in Figs. 48-50. In these depictions, a stripped M-16/AR15 barrel is used. In the present invention, barrel 12 is mounted upon a lock ring 22 which interfaces with the barrel trunnion 26. It should be noted that the barrel 12 is not fused to the lock ring 22, so that generic barrels, with flanges 30 (Figs. 51 and 52), may be used with this invention. A foldable wire handle 24 extends from the lock ring 22 to aid in assembly and disassembly of the barrel structure from the firearm. Mounted over the barrel 12 is the gas piston assembly 17, which comprises, among other things, a piston rod 409. The piston rod 409 is held in place by two rod guides 405, 407, one on the barrel (405) and the other on the barrel trunnion (407).

[00140] Barrel trunnion 26 and lock ring 24 have non-continuous, interrupted thread interfaces 28, 28A (best seen in Figs. 51, 52, 56 and 59) and a locking structure to hold them together. The non-continuous, interrupted thread pattern is preferred as it provides points of quick attachment/detachment to further increase speed. The interruptions may provide as few as one such points, but it is preferred that three or more are used, with an ideal range of 3 to 5 such points. The preferred locking structure is a detent pin (or lock plunger) 25, biased by spring 429, which interfaces with flat ridges 21 on the lock ring 22 (one shown) to prevent rotation, thus keeping the lock ring 22 and barrel trunnion 26 together (Figs. 53 and 55). These ridges 21 must, of course, be manufactured to coincide with the interrupted threads 28, 28A. When held together, the lock ring 22 and barrel trunnion 26 cam the barrel extension flange 430, and thus the entire barrel 12, in place, holding it along an entire 360° arc which is more secure than prior art designs and automatically centers the barrel 12 in the trunnion 26 and therefore keeps the barrel centered adjacent the firing chamber. Lock ring 22 and barrel trunnion do not interface to the point of totally abutting each other, but instead leave a space 440 for the barrel flange 430 and for the barrel rod guide 405 to extend out of the barrel trunnion 26. It should also be noted that lock ring 22 also provides a measure of heat sinking capability to the system to prolong use of the firearm without changing barrels. [00141] In use, depicted in Figs 60A-60D, the barrel 12 is held by the lock ring 22 and trunnion 26. The user unfolds the handle 24 and depresses the lock plunger (Fig. 60B). The user then rotates the handle 24 and associated lock ring 22 until it is freed from the trunnion

26 (Fig. 60C). At that point, the barrel 12 is removed from the trunnion 26 (FIG. 60D). It should be noted that the barrel 12 does not turn in this operation.

[00142] With reference to Fig. 61, the firearm has four major components, namely the barrel 512, upper receiver 514, grip housing 516 and stock 518. Many of the reference numbers pertain to like reference numbers used herein not preceded with a "5", but not all. Internal parts are generally located in the receiver 514 and grip housing 516. A trigger control group 511 and a magazine 513 reside in the grip housing 516 and a short stroke gas piston system 517 and charging system 519 and bolt carrier 515 reside in the receiver 514. The firing pin is also located in the receiver 514. As shown in Fig. 63, barrel 512 rests in barrel trunnion 522 in a cantilevered fashion. Gas piston system 517 resides over the barrel 512. Bolt carrier 515 rests against the barrel trunnion 522 when it is in a rest position. The charging handle 519 resides over the barrel trunnion 522, also abutting the bolt carrier 515, and mounted upon firearm geometry so as to allow movement transverse the barrel 512 and the path of the bolt carrier 515. When stowed, the charging knobs 535 extend beyond the receiver 514 and above the hand guard 520 of the firearm (Fig. 62) on both sides so as to allow ambidextrous use without alteration.

[00143] The charging handle system itself, shown in Figs. 64A-67B and 72, is a non- reciprocating design, which is to say that is usually does not travel with the bolt carrier when the firearm is fired. The charging handle group 519 consists of a charging handle actuator 531, charging handle blade 537, and forward assist lever 533. Charging handle blade 537 resides at a fore end of charging handle actuator 531 and provides support for the charging handle knobs 535, which are secured by pins 536.

[00144] Forward assist lever 533 resides at a distal end of charging handle actuator 531 between two ridges 540, slightly above the surface of the charging handle actuator 531. Angled slot 542 cuts towards the fore end of the charging handle actuator 531 and through ridges 540. The forward assist lever 533 has two ears 544 which reside in the slot 542. Forward assist lever 533 is biased rearward by spring 539 residing between forward assist lever 533 and spring block 538. Ears 544 have an angular orientation (seen in Figs. 64B and 67B) that keep them positioned within the slot 542 and allows for fluid motion of the ears downward as the forward assist lever 533 is pushed forward against spring 539. Forward assist lever 533 is provided with a hook 546 that extends off of distal end of the charging handle actuator 531. Forward assist lever 533 is further secured in the system by a T-bar 533a which, when assembled, resides in two slots 535a fashioned in the charging knobs 535.

[00145] When in default, non-reciprocating, position, shown in Figs 68A-69, the charging handle 519 abuts bolt carrier 515. Should charging handle 519 be pulled back in relation to the firearm, it will push bolt carrier 515 along its path and charge the system. In this position, the charging handle 519 will not travel with the bolt carrier 515 when the firearm is fired as the two are not connected. As can be seen in Fig. 68B, the hook 546 is positioned above a ridge 548 in a notch (not numbered) in the bolt carrier 515. When the forward assist lever is pressed forward, shown in Figs. 70A-71, ears 544 travel along the slot 542 and bias the forward assist lever 531 and hook 546 downward. The hook 546 then engages the ridge 548 (Fig. 70B), linking the bolt carrier 515 to the charging handle 519. This then allows the charging handle 519 to pull the bolt carrier 515 and act as a forward assist to move the bolt carrier 515 back into firing position. Since the forward assist lever 533 is spring biased backwards, releasing the forward assist lever allows the hook 546 to automatically release the ridge 548, uncoupling the charging handle 519 and bolt carrier 515. [00146] In its preferred embodiment, the charging handle system 519 is mounted to the firearm on two rails 550 which reside along the path of travel of the charging handle 519 and the bolt carrier 515 (Figs 73-74B). Figure 14 depicts the system with the charging handle actuator removed. A detent spring 534 is provided in the fore end of the actuator 531 (shown in Figs. 66 and 72). It is secured by pin 532. As can be seen in Fig. 66, ends of the detent spring 534 extend underneath and inward of the charging handle actuator 531. These ends interface with notches 555 provided in the rails 550 (Fig. 74B) to secure the charging handle 519 in its forward position in relation to the firearm, until removed from this position by a user.

[00147] It should also be noted that the barrel trunnion 26 may be manufactured to accommodate any size, caliber, or type of rifle. As such, the barrel trunnion 26 may be manufactured to accommodate individual brand, model, and rifle specifications, including caliber, headspace.

[00148] While the invention has been particularly shown and described with reference to a number of embodiments, it would be understood by those skilled in the art that changes in the form and details may be made to the various embodiments disclosed herein without departing from the spirit and scope of the invention and that the various embodiments disclosed herein are not intended to act as limitations on the scope of the claims.