Over riding chamber impulse average weapon

A recoil-operated, impulse averaging, air-cooled, magazine-fed, automatic weapon. An operating group of the weapon includes a chamber, a bolt, a barrel extension and one or more toggles. The recoil action of the weapon from firing a first round drives the toggles in a motion constrained by a cam way. The toggles then drive the chamber in a linear reciprocating motion ejecting a first round and over-riding the next round. An impulse averaging system controls the speed of the recoil.

FIELD OF THE INVENTION

Embodiments of the invention relate to an automatic weapon. More specifically, embodiments of the invention relate to a recoil operated automatic weapon and a linkless ammunition feed system.

BACKGROUND OF THE INVENTION

Throughout history, military forces have been employed in offensive, defensive, and peace-keeping roles. Recent events have presented a need to perform these roles in tight quarters situations set in urban environments. Accordingly, a need exists for a lightweight weapon.

Lightweight automatic firearms have been produced to meet these needs. However, many lightweight firearms are subject to reduced accuracy resulting from the repeated recoil forces to which the user is submitted when firing in an automatic mode. Therefore, a need exists for a lightweight firearm, that does not sacrifice the accuracy of heavier weapon systems.

SUMMARY OF THE INVENTION

An embodiment of the present invention provides a firearm for firing cylindrically-shaped cased telescoped or case-less ammunition. The firearm comprises a barrel having a longitudinal bore axis, and a bolt that is collinear with the barrel's bore axis and adapted for linear movement between a charged position and a firing position. The movement of the bolt is relative to the barrel and parallel to the barrel's bore axis. The firearm further comprises a chamber that has a cylindrically-shaped ammunition-holding cavity formed within. The ammunition-holding cavity has a diameter sized to receive a cylindrically-shaped round of ammunition, the ammunition-holding cavity is also collinear with the barrel's bore axis. The chamber is also adapted for linear movement between a charged position and a firing position, with linear chamber movement being relative to the barrel and collinear with the barrel's bore axis. In the charged position, the chamber is positioned rearward of and away from the barrel, the bolt is also in its charged position and a forward surface of the bolt is generally coplanar with a forward surface of the chamber, with the bolt occupying the ammunition-holding cavity. In the firing position, a forward surface of the chamber sealingly contacts a rearward surface of the barrel, the bolt is also in its firing position and a forward end of the bolt sealingly contacts a rearward end of the chamber, with the chamber ammunition-holding cavity largely vacated by the bolt.

A further embodiment of the present invention further provides a method of charging a firearm. The firearm of the method comprises a barrel with a longitudinal bore axis, and a generally cylindrically-shaped firing pin having a lug extending from a circumferential surface, a bolt comprising a generally cylindrically-shaped internal cavity, a slot extending from the internal cavity to an external surface of the bolt, and a lug extending from an exterior surface of the bolt. The internal bolt cavity is adapted to accept the firing pin and accommodate linear movement of the firing pin with the firing pin lug extending through the bolt slot. The firing pin's linear movement is relative to the bolt and parallel with the barrel's bore axis. The bolt is collinear with the bore axis and adapted for linear movement to a charged position, with the linear bolt movement being relative to the barrel and parallel to the barrel's bore axis. The firearm further comprises a chamber with a cylindrically-shaped ammunition-holding cavity formed within and having a diameter sized to receive a cylindrically-shaped round of ammunition. The ammunition-holding cavity is also collinear with the barrel's bore axis. The chamber is adapted for linear movement to a charged position, with the linear chamber movement being relative to the barrel and collinear with the barrel's bore axis. In the charged position, the chamber is positioned rearward of and away from the barrel, and the bolt is also in its charged position with a forward surface of the bolt being generally coplanar with a forward surface of the chamber and the bolt occupying the ammunition-holding cavity. The firearm further comprises a sear.

A method associated with this embodiment comprises moving the chamber rearward, away from the barrel and overriding the bolt, until a rearward surface of the chamber contacts the firing pin lug. With the chamber continuing to move rearward, it begins to push on the firing pin lug and push the firing pin rearward toward a rearward end of the bolt cavity, while continuing to override the bolt. The chamber and firing pin continue rearward until a rearward surface of the chamber contacts the bolt lug, at the same time, the forward surface of the bolt is generally coplanar with the forward surface of the chamber, and the firing pin stops moving relative to the bolt. Finally, the chamber and firing pin continue rearward while pushing on the bolt lug and pushing the bolt rearward until the firing pin lug catches on the sear.

Yet another embodiment of the present invention provides a method of firing a round of cased telescoped or case-less ammunition from a firearm. The firearm of this method comprises a barrel having a longitudinal bore axis, a bolt that is collinear with the bore axis and adapted for linear movement between a charged position and a firing position, with the linear bolt movement being relative to the barrel and parallel to the bore axis, and a chamber comprising a cylindrically-shaped ammunition-holding cavity formed therethrough. The ammunition-holding cavity being collinear with the bore axis and having a diameter sized to receive a cylindrically-shaped round of ammunition. The chamber is adapted for linear movement between a charged position and a firing position, wherein the linear chamber movement is relative to the barrel and collinear with the bore axis. In the chamber charged position, the chamber is positioned rearward of and away from the barrel, the bolt is also in its charged position and a forward surface of the bolt is generally coplanar with a forward surface of the chamber, with the bolt occupying the ammunition-holding cavity. In the chamber firing position, a forward surface of the chamber sealingly contacts a rearward surface of the barrel, the bolt is also in its firing position and a forward end of the bolt sealingly contacts a rearward end of the chamber, with the chamber ammunition-holding cavity largely vacated by the bolt.

A method associated with this further embodiment comprises placing the chamber and bolt in their respective charged positions, then begins to move the chamber and bolt to their respective firing positions. Introducing a round of cased telescoped or case-less ammunition between the forward surfaces of the chamber and bolt and the rearward surface of the barrel, before the chamber and bolt reach their firing positions. Restraining movement of the round of ammunition along the bore axis, and relative to the barrel, by trapping the round between the forward surfaces of the chamber and bolt and the rearward surface of the barrel. Moving the round of ammunition to be collinear with the bore axis, then moving the chamber toward the barrel to over-ride the round of ammunition. Sealing the chamber against the barrel, and releasing the firing pin to fire the round of ammunition.

In another embodiment of the present invention, an ammunition feed system is provided. The system comprises an ammunition container having a path for holding a plurality of cased telescoped or case-less ammunition rounds in a single file manner, and an exit for passing the ammunition rounds out of the container. A cylindrical pusher is positioned in and adapted to freely slide through the ammunition path, with the plurality of ammunition rounds being positioned between the exit and the cylindrical pusher. The cylindrical pusher is also adapted to push the ammunition toward the exit. A feed line is connected to the cylindrical pusher and being of a length to extend through the ammunition path and out of the exit, and having a width to be able to be in the ammunition path without disturbing the movement of the plurality of ammunition. A feed line spool is provided, capable of rotating, and positioned adjacent to the exit and adapted to collect the feed line while rotating. A feed sprocket is also provided, capable of rotating, and attached to and collinear with the feed line spool. The feed sprocket is adapted to turn in unison with the feed line spool and comprises radially spaced teeth. When the feed sprocket rotates, the teeth grip and move the ammunition from the container exit to a firearm associated with the ammunition feed system.

A further embodiment of the present invention provides a method of feeding ammunition into a firearm. The method comprises providing a plurality of ammunition rounds in a path, with the path having an exit and a distal end. Pulling a cable through the path containing the plurality of ammunition rounds. Pulling a pusher through the path from the distal end toward the exit by attaching it to the cable, with the pusher being adapted to slide through the path and push the plurality of ammunition rounds toward the exit. When a round of ammunition reaches the exit, presenting the round of ammunition to the firearm.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description is intended to convey a thorough understanding of the invention by providing a number of specific embodiments and details involving an automatic weapon. It is understood, however, that the invention is not limited to these specific embodiments and details, which are exemplary only. It is further understood that one possessing ordinary skill in the art, in light of known systems and methods, would appreciate the use of the invention for its intended purposes and benefits in any number of alternative embodiments. Throughout the specification, the use of the terms “front” or “forward” refer to the muzzle end of the firearm or toward the muzzle, and the terms “rear” or “rearward” refer to the buttstock end of the firearm or toward the buttstock.

Referring toFIG. 1, a lightweight, air-cooled, recoil operated machine gun is provided as an exemplary embodiment of the invention. The weapon100of the preferred embodiment comprises an upper receiver200, a lower receiver300, an operating group400(shown inFIG. 9), and a linkless-ammunition feed system500.

Referring now toFIGS. 1-5C, the weapon100comprises an upper receiver200and a lower receiver300. The upper receiver200and lower receiver300cooperate to at least partially house the internal operating group400within a cavity150. The upper receiver200comprises an external gripping surface202for the operator, left204aand right204bcharger ports, an eject gate208, and upper210and lower212rails.

Charger ports204comprise charger covers106. Left and right charger ports204a,204ballow the charger handle424to be positioned for ambidextrous use of the weapon100. Charger covers206provide a barrier limiting the dirt or other contaminants that may otherwise enter the weapon and jam or limit the operation of the internal operating unit400.

Referring toFIGS. 5A-C, the upper receiver comprises an upper rail210and a lower rail212. The rails210,212are adapted to provide versatile attachment points for a variety of accessories. Such attachable accessories may include, for example, a forward iron sight110, a rearward iron sight112, other scopes and sighting and/or aiming systems113, a tripod or bipod220, bipod mounts222, a pintle118for mounting to a tripod, grenade launchers116, mount214, and slings or sling mounts. Upper receiver200may also include other means for attaching accessories such as a mount214for attaching a handle114or other means for mounting the weapon to any appropriate support.

In an embodiment of the invention, a bipod220is removably mounted to the lower rail212. Bipod mount222allows bipod220to be alternatively moved between a stowed or extended position. In the stowed position, bipod220is positioned against a lower portion of the upper receiver200. In the extended position, bipod220is moved so that the bipod legs224are essentially perpendicular to the upper receiver200. Bipod legs224are extendable and comprise feet226, appropriate for stabilizing the forward section of the weapon on a variety of surfaces. Other variations comprise removable and interchangeable feet, allowing the operator to select feet most appropriate for the environment in which the weapon100will be deployed. Alternatively, bipod220could be permanently mounted to lower rail212or another portion of the upper or lower receiver. Such Bipod assemblies are generally known in the art. Other bipod assemblies may be used.

Referring now toFIGS. 7-8, the upper receiver200and lower receiver300are hingedly connected at hinge102forward of trigger304. The hinge102may comprise any appropriate hinge assembly as would be apparent to one of skill in the art. The two receivers200,300latch together, forming an internal weapon cavity150, which houses the internal operating group400.

When the two receivers200,300are unlatched, they pivot about hinge102, opening the weapon to allow the operator access to the cavity150and internal operating group400. The internal operating group comprises a barrel assembly402, a firing assembly404, and a recoil assembly406. Once the two receivers200,300are unlatched and opened, the recoil assembly406may be removed from the firing assembly404, and the firing assembly404and the barrel assembly402may then be pulled from the firearm upper receiver200for maintenance and/or repair.

The lower receiver300houses the recoil assembly406and includes various control features and an ammunition well310. The control features comprise a pistol grip302, a trigger304, a trigger guard306and a safing lever308. The safing lever may be operable to place the weapon in safe, semi-automatic, automatic, or other firing modes. Such safing levers308and mechanisms are generally known in the art.

An ammunition container502attaches to the ammunition well310, which comprises front314and rear316container guides. Left and right release levers (not shown) allow for removal of container502and can be actuated from either side or from both sides of the weapon.

As illustrated inFIG. 6, embodiments of the lower receiver comprise a buttstock320at the rear end of the weapon100. The buttstock320is movable between a collapsed position320aand an extended position320b. The buttstock comprises a fixed portion322and a movable portion323. The movable portion323telescopes with respect to the fixed portion322. A pin324passes through a groove327in the movable portion323and engages one of a series of recesses326in the fixed portion322. The pin324is biased into the recesses326by a spring325and serves to lock the fixed322and moving323portions of the buttstock320at varying degrees of extension. A lever328is positioned on the under side of buttstock320and the lever328moves pin324between a locked position in which pin324engages one of recesses326and a disengaged position in which pin324disengages from recesses326. Such Buttstock assemblies are generally known in the art, and other Buttstock assemblies may be used.

The upper receiver200and lower receiver300of the preferred embodiment are manufactured from a carbon/epoxy composite. However, the receivers200,300could alternatively be manufactured from any suitable material known in the art.

Referring now toFIGS. 9-11D, the barrel assembly402comprises a barrel410, a barrel handle412, and lugs414. The barrel410is preferably manufactured from Cr—Mo steel with a chromium plated bore. However, the barrel410could be manufactured of other materials known in the art. In addition, the barrel410preferably has a twist ratio of 1 turn per 9 inches of barrel length.

The barrel assembly402further comprises a quick-change feature allowing for quick barrel replacement. The preferred embodiment provides for the entire barrel assembly402to be quickly and simply removed from and a new assembly re-attached to the weapon100in about 10 seconds. The lugs414are located at the breech end of the barrel410, while the barrel handle412is preferably located near the muzzle of the barrel410. It should be noted that the handle may be located anywhere along the length of the barrel410. When the barrel assembly402is attached to the weapon100, the barrel is received in the barrel extender420, the lugs414are mechanically engaged with the barrel extension420, and the handle412is in its stowed position—generally parallel to the barrel410.

As illustrated inFIGS. 10A-10D, to remove the barrel410, the operator first extends the handle412from its stowed position412ato its extended position412b, approximately perpendicular to the barrel410, as illustrated by arrow409. The operator then rotates the barrel410and handle412approximately 90° about the longitudinal axis of the barrel410, as illustrated by arrow411. Rotating the barrel410disengages the lugs414from the barrel extender420, allowing the whole barrel assembly402to be detached from the firing assembly404and removed from the upper receiver200. Barrel replacement takes place in the reverse sequence.

During weapon firing, the handle412is not in contact with the barrel410keeping the handle412cool for ease of handling during barrel removal. For operator safety, the barrel may not be removed while the weapon is charged, nor may the weapon be charged unless a barrel is attached.

Referring toFIG. 11, a variation of the preferred embodiment comprises a concentric collar418instead of a handle412. The collar418is located at the forward end of the upper receiver200engages and unlocks the barrel410. Turning the collar418through a predetermined angle, illustrated by arrow413, unlocks the barrel410from the barrel extender420. Turning the collar418through a further angle enables removal of the barrel410and collar418from the weapon100. Again, barrel410replacement takes place in reverse sequence.

The structure the firing mechanism will now be explained. Referring toFIGS. 9, and12A-15F, some of the major components of the firing assembly include a barrel extension420, a chamber422having an ammunition holding cavity, a charging handle424, a bolt426, a firing pin430, a firing pin spring436, a two-position firing pin latch438, forward and rear chamber toggles440,441, a toggle rail444, a load pawl446, a fixed and a movable load pawl cams450,452, a sear454, a sear link456, and a sear spring458.

The inner surface of the upper receiver200comprises cam ways that interact with the internal operating group400. The left444aand right444btoggle cam ways provides a path for the toggle cam rollers442to follow, a fixed load pawl cam way450provides an ammunition loading path for the load pawl pivot arm448to follow, and a movable load pawl cam way452provides an ejection path for the load pawl pivot arm448to follow. The load pawl pivot arm448follows the fixed load pawl cam452throughout its forward motion as it loads ammunition120into the chamber, and follows the movable cam452as it moves rearward and ejects a spent shell. The movable load pawl cam way452is thus movable between two positions, a by-pass position and an eject position and is biased to the eject position by a spring (not shown). In the by-pass position, the movable cam452is pivoted upward due to the forward movement of the load pawl pivot arm448. In the eject position, the movable cam452is lined up with the fixed cam450, and provides a path for the load pawl pivot arm448to follow when it ejects a spent shell. The interaction between the rollers and cam ways are discussed in greater detail herein.

The forward440and rear441chamber toggles are hingedly connected to each other. The rear chamber toggle441is also hingedly connected to the barrel extension420, and the forward chamber toggle440is hingedly connected to the chamber422. The rear chamber toggle441comprises a roller442, which rides in a toggle rail or cam444. The toggle rail444is attached to the upper receiver's internal surface201, and fixed relative to the other components of the firing assembly404. In addition, it is contemplated that the toggle rail444may be integrally formed with or permanently or removably attached to the interior surface201. As the firing assembly404moves through the firing cycle, the fixed toggle rail444controls the position of the toggles440,441, which, in turn, controls the position of the chamber422relative to the barrel extension420. The load pawl446is also hingedly connected to the barrel extension420and comprises a roller. The load pawl pivot arm448rides in both a fixed load pawl rail450and a movable load pawl rail452. The load pawl cams450,452are attached to the upper receiver interior surface201. The fixed load pawl cam450may be integrally formed with or permanently or removable attached to the interior surface201. The chamber422, bolt426, firing pin430are concentric with each other and are all collinear with the barrel420. In addition, the bolt426is fixed relative to the barrel410, eliminating the need for any complex locking mechanism.

The operating cycle of the weapon begins with charging the weapon. Referring specifically toFIGS. 12A-12B, charging the weapon100for firing, first requires the operator to extend the charging handle424from a stowed position to a ready position (arrow425,FIG. 12A). The charging handle424is then pulled rearward, toward the buttstock320(arrow427,FIG. 12B). Referring toFIGS. 15A-16A, as the charging handle424is moved rearward, the eject port is opened (not shown), the recoil spring462is compressed, and the entire firing assembly404is moved to the sear position and latched in place by the sear454(seeFIG. 15A). In the sear position, the toggles440,441are folded, holding back the chamber422, which creates a clearance between the barrel410and the chamber422. This clearance provides an opening for the next round of ammunition120, which will eventually move upward from the magazine200to be parallel and linear with the barrel410and chamber422.

As shown inFIGS. 13A-13B, the charging handle424can be alternatively positioned on either the right or left side of the weapon for ambidextrous use. In a preferred embodiment, the charging handle424is positioned at an angle α approximately fifteen degrees above horizontal. This provides additional clearance424cbetween the handle424and ammunition container200(FIG. 13B). Alternatively, the charger handle424may extend horizontally from the weapon (FIG. 13A).

With the weapon100charged, it is now ready to fire. The weapon firing cycle may be best understood in relation toFIGS. 14A-15F.

InFIG. 15A, the firing assembly404is in the sear position and the weapon is ready to fire. In the sear position, the firing assembly404is held back by the sear454and the firing pin430is held in a first sear position by the two-position firing pin latch438. The toggles440,441are held in a bent configuration by the toggle rail444(seeFIG. 15B), thus holding back the chamber422. The chamber422butts against a bolt lug427and a firing pin lug432and is completely occupied by the bolt426. To fire the weapon100, the operator releases the firing assembly404from the sear position by pulling the trigger304. This movement pivots the trigger304, pushing the sear link456upward, which then pivots the sear454to release the firing assembly404. Now released, the firing assembly404begins to move forward under force of the recoil spring462. This forward movement pushes the load pawl446under the next ammunition round120and begins to push the barrel410forward with respect to the upper receiver200. The slides relative to the upper receiver in barrel extension tracks445.

Referring toFIG. 15B, the firing assembly404continues forward, pushing the load pawl pivot arm448along the fixed load pawl rail450, which causes the load pawl446to pivot upward. As the load pawl pivot arm448follows the fixed load pawl rail450, it pushes on the bottom of the movable pawl rail452to pivot it upward to its by-pass position and out of the path of the forward moving load pawl pivot arm448. Once the load pawl pivot arm448clears the moving rail452, the moving rail452drops back down to its eject position. This movement begins to lift the round120from the top of the ammunition magazine200. Once the round120is out of the container, the firing assembly has progressed far enough for the firing pin latch438to engage in a firing pin cam (not shown). The cam pivots the firing pin latch438from a first position to a second position, releasing the firing pin430. The firing pin430is now able to proceed under the force of the firing pin spring436. However at this point, the firing pin430is still prevented from proceeding forward by contact between the firing pin lug432and the chamber422.

The chamber422is preloaded forward by the firing pin spring436. Accordingly, as the load pawl446lifts the round120upward, the forwardly biased chamber422traps the round120between the vertical surfaces of the chamber and the barrel. This orients the round120parallel with the chamber and barrel while the load pawl continues to push the round upward until the round is co-linear with the chamber and barrel.

Referring now toFIG. 15C, the firing assembly404continues forward and the load pawl446continues to pivot upward, placing the round120collinear with the chamber422and barrel410. Also at this time, the toggle rollers442are guided by the toggle rail444, rotating the rear toggles441about axis441a, which then causes the forward toggles440to rotate about axis440a. This motion straightens the toggles440,441at the connecting joint439and pushes the chamber422forward. The forward moving chamber422simultaneously takes up the clearance between itself and the barrel410and pushes past the bolt426, overriding the round120. In this manner, the chamber422is continuously occupied by either the bolt426or an ammunition round120, and foreign debris is prevented from entering the chamber422.

At the same time, this movement also creates clearance between the chamber422and the firing pin lug432, allowing the firing pin spring436to push the firing pin430forward. As the firing pin430moves forward, the firing pin lug432engages the firing pin latch438at the second sear position438b. The firing pin cam (not shown) interlocks with the pin latch438to prevent release of the firing pin430until the chamber422is closed. As the chamber422closes, it overrides the round120while the load pawl446drops slightly to clear the chamber422.

InFIGS. 15D and 15E, the chamber422has closed and the assembly404continues forward. The firing pin cam further pivots the firing pin latch438, releasing the firing pin430from the second sear position438b. The firing pin430moves through the bolt slot428and impacts the cartridge primer128(see Figure A), which ignites the cartridge propellant130creating a high-pressure gas to send the bullet122down and out of the barrel410. The recoil force generated by the discharge of the round120pushes the firing assembly404rearward.

InFIG. 15F, the firing assembly404moves rearward. The toggles rollers442are guided by the toggle rail444, rotating the rear toggles441about441a, which then causes the forward toggles440to rotate about440a. This motion bends the forward and rear toggles440,441at the connecting joint439and pulls the chamber422open, away from the barrel410and back over the bolt426. As the chamber422continues rearward, it contacts the firing pin lug432and pushes it back to the rear sear position438a. A firing pin latch spring (not shown) biases the firing pin latch438upward, which secures the firing pin latch438once the lug432is in the rear position.

At the same time, the load pawl pivot arm448moves rearward into movable load pawl rail452to carry the load pawl through its ejection path. The movable load pawl rail452pivot is above the load pawl446pivot which causes the movable load pawl rail452to remain fixed due to a down rotational stop. The moveable rail452guides the load pawl446through a greater range of motion than the fixed cam450, sweeping the load pawl446upward and ejecting the spent cartridge casing126. After the spent cartridge126is ejected through the ejection port, which is open on charging, the load pawl rotates back down its initial sear position. As the firing assembly404continues rearward, the load pawl446moves past the ammunition well310, allowing room for another round120to be presented from the magazine502.

While the firing cycle has been described at six discrete points relating toFIGS. 15A through 15F, these six positions have been described for illustrative purposes only. It should be understood that, in operation, the present invention's firing cycle comprises a smooth and continuous sequence of motion, taking the firing assembly from sear position, to firing the round, and back to sear position.

Referring toFIGS. 16A and 16B, the velocity and travel distance of the barrel410and firing assembly404during recoil is regulated by the impulse averaging recoil system406. The impulse averaging system comprises a recoiling mass, which is comprised of the mass of the moving parts of the internal operating group400(seeFIG. 8), a drive spring462and a dashpot or damper464.

The damper464is connected between the lower receiver300and the firing assembly404and contained within the buttstock320and the upper receiver internal cavity150. The damper464comprises a spring retainer330, a piston rod331, and a buffer body332. The spring retainer330is a long cylindrical tube with an open rear facing end and a closed forward end. The buffer body332is a cylinder with a forward end sealed by a forward end cap333, and a rearward end sealed with a rear end cap334. A shock tube335is contained within the buffer body332and is retained collinear with the buffer body by the forward and rear end caps. The buffer body332and shock tube335assembly is telescopically received in the open end of the spring retainer330. The forward end cap comprises a forward shuttle valve336and valve spring337, and the rearward end cap comprises a rearward shuttle valve338and valve spring339. The rear end cap further releasably secures the recoil assembly to the buttstock. The spring retainer and the rear end cap comprise flanges340that retain the drive spring.

The buffer body and shock tube comprise hydraulic fluid. The shock tube further comprises a series of orifices341in its circumferential side that allow the hydraulic fluid to pass from the shock tube to the buffer body and vice versa. The piston rod331extends through an opening in the closed end of the spring retainer330, through a sealed opening in the forward end cap333and into the shock tube332and past the open end of the spring retainer330, terminating in a piston head344. The piston rod331has a forward end that comprises two flanges. A first flange342releasably secures the recoil assembly to the barrel extension and a second flange343prevents the piston rod from extending too far into the spring retainer.

The damper464acts as a velocity regulator that controls the forward velocity of the firing assembly404, and ensures that the weapon fires at a consistent forward velocity. The damper464controls the peak load on recoil by monitoring the recoil velocity and providing more resistance if the velocity is high and less if the velocity is low. The recoil system406of the present invention allows the weapon100to be fired at any attitude (+/−90°) and with a large friction or impulse variation from the round120.

When the weapon is charged, the recoil assembly is compressed, the spring462is compressed, the shock tube335and buffer body332are pushed into the spring retainer, and the piston rod331is deeply extended into the shock tube335. This orientation places a high percentage of the hydraulic fluid forward of the piston rod head344and little to no hydraulic fluid rearward of the piston rod head. When the trigger is pulled, the main spring462pushes the spring retainer330, piston344, and barrel extension forward. While moving forward, the piston pushes on the hydraulic fluid. The bulk of the hydraulic fluid moves from forward of the piston head344through the shock tube orifices341axially along the outer surface of the shock tube, between the shock tube335and buffer body332, and back into the shock tube through more orifices, rearward of the piston head.

As the piston moves forward, there are fewer and fewer orifices for the piston to push hydraulic fluid through, this results in a gradual reduction of flow area controlled by the fixed orifices. Also, the spring loaded shuttle valve336in the forward end cap333initially remains open presenting a large flow area. When the differential pressure across the valve exceeds the spring pressure, the shuttle valve336closes to greatly reduce the flow area. The combination of reduction of the fixed orifices and the shuttle valve orifice closing, creates greater resistance to fluid flow and therefore a greater resistance to the forward motion of the barrel extension. The fixed orifices341and the shuttle valve336and spring462are designed such that the forward momentum of the barrel extension remains constant, independent of external forces such as gravity or increase mechanical resistance such as friction.

Once the weapon fires, the barrel extension moves rearward driven by momentum of the fired round minus the forward motion momentum. The piston344once again pushes the hydraulic fluid. The bulk of the hydraulic fluid moves from rearward of the piston head through the fixed orifices341axially along the outer surface of the shock tube335, between the shock tube and buffer body332, and back into the shock tube, through more fixed orifices341, forward of the piston head. As the piston moves rearward, there are fewer and fewer orifices for the piston to push hydraulic fluid through, this results in a gradual reduction of flow area controlled by the fixed orifices. The rear spring loaded shuttle valve338in the rearward end cap334initially remains open presenting a large flow area. When the differential pressure across the valve exceeds the spring pressure, the shuttle valve closes to greatly reduce the flow area. The combination of reduction of the fixed orifices and the shuttle valve orifice closing, creates greater resistance to fluid flow and therefore a greater resistance to the rearward motion of the barrel extension. The fixed orifices341and the shuttle valve338and spring462are designed such that the rearward momentum of the barrel extension remains constant, independent of external forces such as gravity or increase mechanical resistance such as friction. It also is design to minimize the load to approximately 33 lbf with a large range of ammunition round impulse variation. Additional embodiments of recoil systems are described in U.S. Pat. Nos. 6,343,536 and 6,644,168, each of which is hereby incorporated by reference in its entirety.

FIG. 17is a diagrammatic representation of the counter recoil cycle as the operating group moves from the fully retracted, ready to fire, Sear position to the fully forward Fire position.FIG. 18shows the recoil cycle as the operating group moves from the fully forward, Fire position to the fully retracted, Sear position. Assuming that the Sear position defines the origin of movement or zero position, in a preferred embodiment, the steps of the counter recoil cycle occur at approximately the following distances from the Sear position: Sear at 0.0 in.; Begin Lift at 0.65 in.; Begin Chamber Closure at 0.65 in.; Capture Round at 0.75 in.; End Lift at 1.15 in.; End Chamber Closure at 2.05 in.; Begin Firing Pin Drop at 2.29 in.; and Fire at 2.3 in. The steps of the recoil cycle occur at approximately the following distances from the Sear position: Fire at 2.3 in.; Begin Chamber Opening 2.05 in.; Begin Indexing at 1.3 in.; End Opening at 1.15 in.; Begin Eject at 1.1 in.; End Eject Round at 0.5 in.; and Sear at 0.0 in. Alternatively, these distances can be adjusted or rearranged in accordance with the knowledge of one skilled in the art.

In the embodiments described herein, the rounds enter the cycle from the bottom and exits from the top. Unlike known weapons where one round must be removed before the next round can be fed, feeding a round into the weapon will force out any rounds remaining in the breech opening. This prevents multiple feed issues during misfires and immediate action. A misfire requires only recharging the weapon which positively clears the round out of chamber and the feed path. These features provide a more reliable weapon in the field and easier operator training.

Referring now toFIGS. 19-21, the preferred embodiment further comprises a linkless ammunition feed system500. The ammunition feed system500comprises an ammunition container502, a feed sprocket assembly504, and a feed actuation assembly506.

In the preferred embodiment, The ammunition container502is a two-piece design having a front portion508and a rear portion510. Container sidewalls512may be integrally formed with either the front508or rear510portions, or both. The ammunition container502has a capacity of 150 rounds of ammunition, though higher or lower capacities containers502are possible. The container502may be made from glass and PTFE filled nylon or other appropriate material. A translucent or clear material preferably forms the rear portion510, allowing the operator to view the number of rounds remaining in the container.

The ammunition container502further comprises parallel front and rear interior surfaces514,516, with one or more interior walls518extending orthogonally between the front and rear interior surfaces514,516. A space is provided between the interior walls518to form an ammunition path520. In the preferred embodiment, the interior walls518cooperate to form a single, convolute ammunition path520beginning at some position within the container502and terminating at a discharge opening522and feed sprocket assembly504. Embodiments of the ammunition path520extend in a generally spiraling coiled layout with no sharp turns or corners. However, the ammunition path520can be configured in any shape or layout that allows the ammunition to freely feed through the path520as the weapon100is fired. The ammunition container502also comprises a discharge opening522to allow the ammunition rounds120to pass from the ammunition container502into the cavity150created by the upper and lower receivers200,300for presentation to the load pawl446.

The feed sprocket assembly504is attached to the ammunition container at the discharge opening522and comprises a feed sprocket524, a drive wheel526, a back drive wheel528and pawl530, a spool532, and a feed cable534. The feed sprocket524, drive wheel526, back drive wheel528and pawl530, and spool532are linearly arranged and rotate about the same axis of rotation504a, and also rotate in unison. The spool532acts as a spool to collect the feed cable532. The feed sprocket524and back drive wheel528are positioned at one end of the spool532, while the drive wheel526is positioned at the opposite end. The feed cable534is preferably made of steel or another material of appropriate strength. One end of the cable534is attached to a cylindrical pusher (not shown), which pushes the ammunition rounds120through the ammunition path520as the feed cable534is taken-up by the spool532. The feed cable534collects on the spool532in a single layer to prevent pitch change. This ensures that one of rotation of the spool532will consistently correspond to a linear displacement of a single round of ammunition120, regardless of the location of the last round within the ammunition path520. This also ensures that the feed sprocket524is continually supplied with the next available round120. The feed cable is threaded from the spool532through the ammunition path520on the outside of the rounds120. As the cable534is fed through the ammunition path520during firing cycles, the rounds120serve as low friction bearings allowing the cable to turn the corners in the ammunition container and not bind.

As the drive wheel526rotates, the feed sprocket524and spool532also rotate, winding the feed cable534about the spool532. As the feed cable534is taken up on the spool532, it pulls the cylindrical pusher through the ammunition path520. The cylindrical pusher pushes all preceding rounds of ammunition through the ammunition path toward the discharge opening522and feed sprocket524. Thus, eliminating the need to link the rounds of ammunition together. As each individual round of ammunition120approaches the feed sprocket524, the teeth of the sprocket524engage the round120. As the sprocket524continues to rotate, it lifts the round120into the receiver cavity for presentation to the load pawl446. The back drive wheel528and back drive pawl530ensure that the feed sprocket524and spool532will not reverse rotation during the weapon firing cycle.

The feed system500also comprises a driving slide536and pushrod540. The pushrod540is slidably attached to the ammunition container502and is biased in an extended or up position by a return spring (not shown). The pushrod540comprises a pawl to engage with and turn the drive wheel526.

The driving slide536is an elongated member, with a first end536bpivotally connected to the interior surface201of the upper receiver200and a second, distal end536a. The driving slide536further comprises a tappet538on its underside, at the distal end536a. The length of the driving slide is sufficient that the distal end536aand tappet538move in a generally linear and vertical fashion when the slide536pivots.

When the driving slide536and pushrod540are in their initial position, they are biased upward by the spring544. As the firing assembly404moves rearward during the recoil or while the weapon is being charged, a feed system cam or roller on the barrel extension420engages with the driving slide536to force it to pivot, moving the tappet538downward. The tappet538forces the pushrod540down, compressing the return spring544. As the pushrod540is driven down, the drive pawl542engages and turns the drive wheel526, which sets the spool and feed sprocket in motion as described herein, presenting a round120to the load pawl446.

With the weapon100now in the sear position, the trigger304is pulled (or if the trigger304remains pulled when the weapon is in its automatic setting) and the firing assembly404moves forward, the feed system cam/roller moves away from the driving slide536, allowing the return spring544to return the pushrod540and driving slide536to their initial position. This also places the drive pawl542in a position to turn the drive wheel526during the next cycle. Another variation provides the driving slide536with a spring to assist in returning it to its initial position.

It should be noted that the weapon100is also capable of utilizing a number of different ammunition containers502. An alternative embodiment comprises a conventional, single column, ammunition magazine capable of holding twenty-five ammunition rounds120.

As illustrated inFIGS. 22-24, a preferred embodiment of the weapon utilizes a substantially cylindrical ammunition round120. The round120comprises a bullet or ball122, a forward cap124, a cartridge case126, a primer128, a propellant charge130, a primer retainer132, a retainer ring134, and a stand-off spacer136.

It will be apparent to those skilled in the art that various modifications and variations can be made in the method of manufacture of the present invention and in construction of this automatic recoil operated weapon without departing from the scope or spirit of the invention. Embodiments of the invention are intended for use in multiple weapon configurations utilizing various ammunition calibers and fulfilling a variety of purposes. For example, possible configurations include, but are not limited to, light machine guns, long and short automatic rifles, and carbines.

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification be considered as exemplary only.