Abstract: Firearms with gas piston assemblies have a receiver defining a passage receiving a reciprocating bolt assembly, a barrel defining a barrel axis and extending from the receiver in a forward direction and defining a barrel gas aperture, a gas block connected to the barrel and defining a piston bore in communication with the gas block bore, a piston assembly having a forward end operably engaged to the piston bore and a rear end operably engaged to the reciprocating bolt assembly, the piston assembly having a piston closely received in the piston bore and having a piston rear end, the piston assembly including an elongated intermediate rod having an intermediate rod forward end registered with the piston rear end and an intermediate rod rear end, and the piston assembly including a rear portion having a forward end registered with the intermediate rod rear end and a rear portion.

Abstract: An improved gas piston system for the automatic loading of a rifle, especially a rifle of the M-16/AR-15 type. The system employs a barrel nut, or an adaptor to a barrel nut, that has been modified to secure one end of a gas piston system. The other end of the gas piston system, namely the piston rod, engages, either directly or indirectly, the key on a bolt carrier group. This configuration positions the gas piston system at a point starting near the barrel nut and extending to the bolt carrier group of the rifle, while a gas tube extends from the gas block to the gas piston system a point near the barrel nut.

Abstract: A gas-delayed blowback firearm includes a lower receiver and an upper receiver releasably coupled thereto. A barrel having a cartridge chamber, an axial bore, and a barrel gas port is secured to the upper receiver. A bolt assembly in the upper receiver reciprocates between a forward in-battery position and a rearward position. A timing block is secured to the bolt assembly. A cylinder housing with an internal gas chamber and a cylinder gas port is secured to the upper receiver. A gas passageway fluidly communicates the barrel gas port with the cylinder gas port. A plunger in the gas chamber is secured to the timing block. The plunger reciprocates with the bolt assembly. Discharge of a cartridge received in the cartridge chamber temporarily pressurizes the gas chamber, applying a forward force to the plunger which causes the plunger to delay rearward travel of the bolt assembly.

Abstract: A training pistol having a rigid barrel and operating with a conventional blowback system, including a frame, a slide and a barrel, including a slide stop device, a firing pin assembly and preferably including a slide lock which can be moved into a disassembly position in which it releases the movement of the slide toward the front. This release can only be achieved if there is no magazine in the magazine well of the frame and the slide is stopped. The barrel is fastened in the frame by a locking device that can be brought into a release position in which it releases the barrel. Additionally an unlocking gap is provided between the barrel and the slide, and when the gap is overcome, after the slide lock has moved into the disassembly position, an unlocking ramp provided on the slide forces the locking device into the release position.

Abstract: The invention relates to a gas piston for a weapon, which is characterized by a spring introduced in the gas piston and a plunger, which engages on one end of the spring, wherein the spring is supported by the other end at the end of the gas piston opposite the plunger. This gas piston can be a component of a gas piston assembly having a counter piston, which is for use in a weapon. The gas piston or the plunger is supported e.g. on the weapon housing. With the special construction of the gas piston or the gas piston assembly formed with same, the gas piston can be transferred from a working position into a resting position within a weapon housing of the weapon.

Abstract: A mechanically coupled buffer and carrier for a firearm includes an interlocking feature on each of the buffer and carrier such that the buffer and carrier are mechanically coupled to prevent carrier tilt and buffer bounce. The interlocking features are brought together to mechanically couple the buffer and carrier during the assembly process of the firearm as the upper receiver is mounted to the lower receiver.

Abstract: A system for an adjustable gas block. The gas block body has a main chamber fluidly coupled to a gas aperture which is fluidly connected to a plunger channel and a gas return path. Downstream of the gas block body is a plunger assembly which includes a ring and a plunger. Further downstream is an adjustment knob which is coupled to the gas block body and which is adjustable upstream and downstream relative to the gas block body. The volume of plunger inserted into the channel path is controlled by the adjustment knob.

Abstract: A mechanism for preventing a partially inserted magazine from accidently ejecting from the firearm. The improved firearms include any type of projectile weapon that employs a magazine to provide ammunition and include rifles and pistols. An improved magazine catch that includes both the primary latch and a safety latch. A method for engaging a magazine to a firearm for providing the firearm with ammunition without unintentionally dropping the magazine due to incomplete insertion.

Abstract: A semiautomatic shotgun comprising a receiver, a barrel, a forward gas block assembly attached to the barrel, a slider assembly rearward of the gas block assembly extending into the receiver. Upon firing a shotshell the explosive gases in the barrel are diverted through two ports into the gas block assembly, specifically into a pair of lateral pressure relief valves positioned on both sides of the barrel. The pressure relief valves further having a gas pathway to a piston chamber. A piston is forced rearwardly and engages a slider of the slider assembly that is linked to a breech block in the receiver. The breech block loads unfired shells and ejects the fired shells accomplishing the semiautomatic recycling. The dual pressure relief valves actuate to moderate and limit the gas pressure that enters the piston chamber when using shotshells of different power levels thereby providing consistency in the recycling operation.

Abstract: Method and tool for promptly aligning the mating port of a gas block with the gas port of a rifle barrel. The prompt alignment of the mating port and gas port is accomplished by using an alignment tool have an alignment port and an alignment slot. The alignment tool is inserted into the gas block such that the alignment port is centered over the mating port and that a portion of the alignment tool protrudes from the gas block. The top surface of the alignment tool is marked circumferentially and the forward end of the gas block is marked perpendicular to the alignment slot. The alignment tool is then removed from the gas block and affixed to the rifle barrel such that the alignment port is centered over the gas port. The barrel is marked through the alignment slot in line with the circumferential marking on the top surface of the alignment tool.

Abstract: A system for an adjustable gas block. The gas block body has a main chamber fluidly coupled to a gas aperture which is fluidly connected to a plunger channel and a gas return path. Downstream of the gas block body is a plunger assembly which includes a ring and a plunger. Further downstream is an adjustment knob which is coupled to the gas block body and which is adjustable upstream and downstream relative to the gas block body. The volume of plunger inserted into the channel path is controlled by the adjustment knob.

Abstract: Provided is a modular adapter for a firearm receiver that has a standardized threaded socket for mounting a tubular extension or stock support. The adapter includes a base plug configured to threadably engage the threaded socket of a receiver and a modular adaption element attached to the base plug and against a rear surface of the receiver. The adaption element presents an attachment means for attaching an accessory, such as a stock, to the adaption element.

Abstract: A heat displacement tool firearm accessory, and a method for mounting such a firearm accessory to a firearm, the heat displacement tool providing a frame, including a base for mounting along a firearm mounting rail, the frame defining a generally hollow core adapted to receive and dissipate firearm barrel heat. The heat displacement tool is at least half the length of the firearm barrel and is capable of being mounted in a location between a firearm barrel and an optic or rear sight, so as to reduce or eliminate barrel mirage.

Abstract: A gas operated firearm barrel has a gas port angled through the wall thereof at an angle from adjacent the barrel muzzle rearward to the barrel bore to thereby allow the shortening of the barrel while maintaining the distance of the gas port bore opening from the barrel muzzle. The process of making a gas port in a barrel in accordance with the present invention is also taught.

Abstract: An apparatus for adapting a firearm for supersonic and subsonic ammunition. The apparatus includes a housing with channels for receiving propellant gas for cycling the firearm and for regulating the pressure of the gas that cycles the firearm. The housing includes a piston in a chamber that constricts the flow of gas when the barrel pressure exceeds a predetermined value. The apparatus includes a spring for applying force to the piston so that the piston position adjusts based on pressure of the gas for each type of ammunition. The method includes steps for manufacturing a firearm to incorporate the apparatus.

Abstract: A gas block assembly for a firearm comprises a cylinder chamber fluidly coupled to the bore of a barrel of the firearm through a gas inlet port. A spool-type balancing piston is disposed for reciprocation within the cylinder chamber between gas transmitting and bypass positions. A spring stack acts on the balancing piston to bias same toward the gas transmitting position. The gas cylinder receives a gas pressure from the barrel when a projectile is fired. When the pressure exceeds a predetermined threshold, the gas block assembly vents the excess gas pressure either into the barrel of the firearm or to atmosphere or into an associated sound suppressor. The balancing piston is designed with a counter-balance chamber. Gas pressure routed into the counter-balance chamber works in conjunction with the spring stack to urge the balancing piston toward its gas transmitting position.

Abstract: A firearm impingement apparatus that includes a gas flow control member that is operable to provide incremental adjustment of gas flow within the gas block of the firearm impingement apparatus wherein the gas flow control member is configured to provide calibrated rotational movement thereof. The gas flow control member further includes a first portion, second portion and third portion contiguously formed. The first portion includes a plurality of longitudinal indentations circumferentially disposed thereon. The second portion has a diameter that is less than that of said first portion and said second portion. A mounting member is present adjacent an opening of a channel and includes a control pin biasly mounted therein that is operable to engage the gas flow control member. The control pin engages the longitudinal indentations to provide calibrated rotational movement of the gas flow control member.

Abstract: A rifle apparatus and method wherein the rifle includes a replaceable, threaded, adjustable barrel assembly which is configured for quickly changing the barrel length of the rifle, converting the rifle for using a different caliber of ammunition, and/or accurately determining and quickly setting the headspace in the firing chamber of the weapon for firing the new ammunition. Further, the rifle apparatus preferably also includes a replaceable lower receiver with a well opening and a corresponding magazine retention and release assembly for receiving a magazine clip for the caliber of ammunition fired by the replaceable barrel.

Abstract: The invention relates to a semi-automatic firearm comprising a hand stock nut (1), bracket (6), piston (7), magazine tube plug (8), magazine tube (9), gas tube (10), mechanism (11), lock bolt (12), body (13), lock (14); bolt arm (15), hand stock (16), barrel cap (17) and barrel (18). In order to enable the use of cartridges with different loads and to reduce the recoil, said firearm comprises a valve piston (5) connected with the piston (7) between the gas tube (10) and magazine tube (9) and the hand stock nut (1). Depending on the pressure generated by the cartridge the valve piston (5) is able to release excess gas through discharge holes (20).

Abstract: Provided in one aspect is an annular gas ring within or adjacent a barrel to increase the efficient transfer of pressurized gas to one or more gas ports, which may communicate the high-pressure gas to a piston to cycle the action of the firearm. Provided in another aspect are gas ports may adjacent the chamber, which may communicate pressurized gas from near the chamber to distally-extending gas tubes that communicate the pressurized gas to a distally located piston to cycle the action. A modular gas system is provided comprising a coupler that couples a barrel with a chamber and forms there-between an annular gas ring with ports that communicate pressurized gas to separate longitudinally-extending cylindrical gas tubes that feed into a gas block that supports the barrel and forms the cylinder for the piston.

Abstract: A firearm having a gas piston system includes a bolt carrier, an adjustable gas piston block located forward on the firearm and an over-the-barrel spring and guide rod arrangement, all of which is housed and contained in a top rail that runs the length of the firearm and that maintains the alignment of these firearm components. The firearm also includes an ambidextrous, non-reciprocating charging handle located forward on the firearm and positioned within the top rail for charging the firearm.

Abstract: Disclosed herein is a modified rifle bolt carrier allowing a selectively openable vent/valve at the location where exhaust gas is pressurizing the bolt carrier 80 to control carrier speed under suppressed fire in a first valve position or unsuppressed fire in a second valve position. A valve core is disclosed which may be rotated 180° to an “open” setting for non-suppressed fire from its position in a “closed” position for suppressed fire. The modified bolt carrier will allow an operator of the firearm to adjust for a suppressor without changing the gas block or having to modify or adapt the front end of the firearm.

Abstract: A stock and recoil system for a firearm includes a lower receiver, a bolt carrier, and a stock assembly. The bolt carrier is reciprocally movable along an axis within an upper receiver carried by the lower receiver and includes a tubular rearward end defining a cavity with a rearwardly directed opening. The stock assembly is coupled the lower receiver and includes a receiver extension coupled to the lower receiver and aligned on the axis. An action spring is carried within the receiver extension and extends therefrom into the tubular rearward end of the bolt carrier. The action spring is movable between a compressed configuration and an expanded configuration during the firing cycle of the firearm. A butt plate is adjustably coupled to the receiver extension and is movable between an extended position and a collapsed position.

Abstract: A gas operating system for a firearm has an energy transmission facility and a gun barrel having a lateral aperture. The energy transmission facility and the lateral aperture have gas communication between them. The gun barrel and the energy transmission facility are mechanically decoupled such that the energy transmission facility does not impede flexing of the gun barrel. All forward forces generated by the energy transmission facility may be transferred from the energy transmission facility to a self-loading facility. The energy transmission facility may include a gas block having a sleeve that is slidably disposed on the gun barrel. The energy transmission facility may include a gas block and a tubular body extending from a receiver to the gas block, one end of the tubular body being slidably received in the gas block. The energy transmission facility may also include the tubular body receiving a gas piston.

Abstract: A firearm can have a bolt having a plurality of locking lugs that are configured to have a shear area that is at least approximately 1.3 times that of a standard M16/M4. A piston can be formed on the bolt and can have a plurality of rings that are configured to cooperate with the piston to mitigate gas leakage past the piston. Each of the rings can have a key formed thereon and a gap formed therein such that the gap of one ring is configured to receive at least a portion of the key of another ring. The bolt carrier can have a double cut cam.

Abstract: An improved bolt and bolt carrier with integral gas key having an extension nozzle threadedly secured and pinned to the gas key for use with a direct gas operated firearm is provided. The extension nozzle is designed to receive a portion of the host firearm's gas operating system. The firing pin retaining pin is oriented so as to expose its widest profile to the firing pin's annular flange, increasing its service life. The bolt has a plurality of lugs extending from its forward end. The extractor recess is constructed so that the face of the bolt is round and the adjacent lugs fully supported. The extractor engages approximately 17% more of a seated ammunition cartridge's rim as compared to the prior art AR15/M16 extractor. The result is an improved bolt and bolt carrier which provides for increased operational reliability.

Abstract: An eccentric rail mounting system is disclosed. In various embodiments, this system comprises an eccentric rail nut for off-center mounting of a rail on a firearm. The eccentric rail nut has an exterior surface that defines a central axis of the nut and a main bore that defines a central axis of the main bore that is displaced from the central axis of the nut. Components and methods are disclosed in a variety of embodiments.

Abstract: A retrofit apparatus is disclosed for a gas-operated reloading firearm having a pressure control unit to operate the firearm in either manual or semi-automatic operation. The pressure control unit is coupled to the reloading unit to reduce a gas flow to the reloading unit in a first configuration and allow the gas flow to the reloading unit in a second configuration. A controller is coupled to the pressure control unit to operate the firearm in the first or second configuration. The firearm operates in a first configuration requiring manual operation until it receives continuous manual actuation to enable the reloading unit in a second configuration.

Abstract: A cartridge gas energized firearm mechanism has a receiver assembly having upper and lower receivers. A bolt carrier is moveable within the upper receiver and has a wall structure having a planar gas key seat surface intersected by a gas port. A gas key is mounted to the bolt carrier and has a planar gas key surface in face-to-face seating engagement with the planar gas key seat surface of the bolt carrier, thus establishing a planar surface interface. The gas key has a cartridge gas supply passage in gas communication with the gas port. A tubular seal member is positioned in sealing engagement within seal receptacles of the bolt carrier and gas key and prevents cartridge gas leakage through the planar surface interface.

Abstract: A firearm having a gas piston system includes a bolt carrier, an adjustable gas piston block located forward on the firearm and an over-the-barrel spring and guide rod arrangement, all of which is housed and contained in a top rail that runs the length of the firearm and that maintains the alignment of these firearm components. The firearm further includes components that provide full auto firing capability. These components include a specially designed auto bracket that cooperates with a modified bolt carrier and a modified upper receiver.

Abstract: A fixed-barrel, gas-operated firearm having its barrel concentrically mounted within a pressure tube enclosing substantially all of the moving parts of the firearm's action. A gas cup reciprocates under the influence of propellant gas pressure when the firearm is fired, driving slide members that link the pressure cup to the firearm's bolt rearward within the pressure tube, unlocking the breech, rotating and retracting the bolt, discharging the spent cartridge casing and then advancing the bolt to chamber a new cartridge.

Abstract: A modified bolt carrier for automatic recoil rifles and pistols preferably includes a shortened bolt carrier, a shortened buffer tube, a modified bolt key and an end cap. The shortened buffer tube is shortened by cutting-off a straight portion of a prior buffer tube. The modified bolt key includes a prior art bolt key, a rod yoke, a pair spring rods, a pair of compression springs, a spring support disc and a spring plug. The spring plug is biased outward from the shortened bolt carrier with the pair of compression springs. The modified bolt key is attached to the shortened bolt carrier and retained in upper and lower receivers of an automatic recoil rifle or pistol. The bolt spring is slipped over the spring plug and the bolt spring is retained by securing the end cap to the lower receiver with a lock pin.

Abstract: A magazine well for a firearm having an angled spine receiving portion. A charging handle for a firearm having latch that extends below a bottom surface of a crossbar. A bolt carrier for a firearm having a pair of vent holes disposed in the indented portion and at least one additional vent hole on indented portion adjacent to the pair of vent holes. A bolt catch for a firearm having a receiving portion curved to match the contours of a human thumb. A scope assembly for a firearm having markers on a scope and amount that correspond to the same radial positions. A bolt for a firearm having a plurality of ribs disposed on a main body and extending from a front end toward a tail portion of the bolt.

Abstract: An improved bolt and bolt carrier with integral gas key having an extension nozzle threadedly secured and pinned to the gas key for use with a direct gas operated firearm is provided. The extension nozzle is designed to receive a portion of the host firearm's gas operating system. The firing pin retaining pin is oriented so as to expose its widest profile to the firing pin's annular flange, increasing its service life. The bolt has a plurality of lugs extending from its forward end. The extractor recess is constructed so that the face of the bolt is round and the adjacent lugs fully supported. The extractor engages approximately 17% more of a seated ammunition cartridge's rim as compared to the prior art AR15/M16 extractor. The result is an improved bolt and bolt carrier which provides for increased operational reliability.

Abstract: A buttstock assembly configured to work in conjunction with a compact buffer assembly consisting of a buffer tube, spring and bolt carrier with an integral buffer is provided. The buttstock assembly, buffer tube and bolt carrier are configured to work with AR15/M16 type firearms and their derivatives. By incorporating the buffer onto the bolt carrier, which is used in conjunction with a buffer tube of reduced length, the overall length of the host firearm is reduced by approximately 3.2 inches. No permanent modification need be made to the host firearm in order to utilize the compact buffer assembly and buttstock assembly disclosed herein.

Abstract: A firearm having a gas piston system includes a bolt carrier, an adjustable gas piston block located forward on the firearm and an over-the-barrel spring and guide rod arrangement, all of which is housed and contained in a top rail that runs the length of the firearm and that maintains the alignment of these firearm components. The firearm further includes components that provide full auto firing capability. These components include a specially designed auto bracket that cooperates with a modified bolt carrier and a modified upper receiver.

Abstract: A firearm having a gas piston system includes a bolt carrier, an adjustable gas piston block located forward on the firearm and an over-the-barrel spring and guide rod arrangement, all of which is housed and contained in a top rail that runs the length of the firearm and that maintains the alignment of these firearm components. The firearm also includes an ambidextrous, non-reciprocating charging handle located forward on the firearm and positioned within the top rail for charging the firearm.

Abstract: A weapon system includes a receiver and an operating group with a barrel extension arranged to axially translate relative to the receiver. In the firing condition, the op-rod assembly and bolt assembly are driven by the drive spring such that the round is guided into the chamber and the op-rod assembly and bolt assembly are locked to the barrel extension and a forward momentum of the op-rod assembly is imparted to the operating group and the round is fired. A portion of an impulse stops the forward momentum of the operating group. In the recoil condition, the operating group is driven rearward by the remaining portion of the impulse, the gas accelerator imparts additional rearward momentum to the op-rod assembly and bolt assembly and stops rearward momentum of the barrel and barrel extension, and the op-rod assembly and the bolt assembly are stopped by the drive spring.

Abstract: A firearm includes a receiver defining a receiver bore and a bolt carrier disposed in the receiver bore. The bolt carrier is moveable relative to the receiver along a longitudinal axis between a firing position and a rearward position. A hand guard is coupled to the receiver and an elongated member is fixed relative to the bolt carrier in the hand guard. A handle assembly is slideably engaged with the elongated member in the hand guard and the handle assembly is moveable toward the receiver to define a charging motion. The bolt carrier presents a first surface and the handle assembly terminates at a terminal surface aligned with the first surface along the longitudinal axis. The terminal surface of the handle assembly abuts the first surface of the bolt carrier when the handle assembly is moved in the charging motion.

Abstract: A convertible gas piston conversion system for the AR-15, AR-10, or their variant rifle platforms is provided to convert the platform from a direct impingement gas system to a piston driven operating system. The conversion system includes a gas block having a barrel bore and two piston cylinder bores one on either side of the gas block. One of the piston cylinder bores is for utilization of the AR-15 rifle and the other of the piston cylinder bores is for utilization of the AR-10 rifle, making this piston system convertible for either the AR-15, AR-10, or any of their variant rifle platforms. A piston cylinder is inserted into the gas block via the piston cylinder bore and a piston is actuated inside the piston cylinder to cycle the rifle. A connecting link is coupled between the piston and an op-rod making the gas systems length adjustable by simply replacing the connecting link.

Abstract: A rifle having a receiver with an integral hand guard and a barrel. The barrel is connected to the receiver. The hand guard extends over and surrounds the barrel. A removable hand guard is attached to the receiver by an attachment that stably holds the removable hand guard to the receiver. The attachment is arranged for allowing detachment and removal of the removable hand guard from the receiver without removal of fasteners.

Abstract: A method of operating a gas operated automatic or semi-automatic weapon that has a bolt that locks by a partial rotation of the bolt with respect to a bolt carrier, the bolt carrier in communication with a gas port on the barrel of the weapon, the method comprising utilizing the gas pressure from a cartridge received from a port in the barrel to unlock the bolt, and utilizing the expansion of a telescoping cartridge in the chamber to recycle the weapon after the bolt is unlocked. In embodiments the cartridge is a 5.56 mm cartridge. In embodiments, the propellant driving the projectile does not provide enough gas pressure to recycle the weapon and the telescoping cartridge supplements the needed power for recycling sufficient to accomplish the recycling. The invention include the telescoping cartridge providing a projectile with lethal energy and recycle capability for gas operated rifles. The subsonic cartridge may have at least 80 ft lbs of energy and operates subsonically.

Abstract: A cam pin system, includes a cam pin comprising a first cylindrical portion having a first length and a first diameter and a second cylindrical portion concentric with the first cylindrical portion and having a second diameter larger than the first diameter, the second cylindrical portion comprising a through-hole to accommodate the passage of a firing pin. The system includes an end plate detachably connected to the first cylindrical portion of the cam pin, a cylindrical bushing encircling the first cylindrical portion and having an outside diameter approximately equal to the second diameter and a bushing length approximately equal to the first length, and lubricant between the cylindrical bushing and the first cylindrical portion. The cam pin system is configured so that the cylindrical bushing can rotate freely about the first cylindrical portion.

Abstract: An adjustable gas block for a gas operated firearm offering a means to adjust a volume of gas directed to the host rifle's operating system. The adjustable gas block provides two positions of adjustment that are selectable based on the presence of a pressure increasing device being mounted on the firearm. A first position provides an optimal volume of gas into the gas operating system absent a back pressure increasing device. A second position usable in the presence of a back pressure increasing device causing venting of a portion of the volume of gas into a secondary chamber prior to release into the atmosphere. The amount of gas received by the operating system due to venting is reduced to a volume that is substantially equal to the volume of gas that would be received by the operating system absent a back pressure increasing device.

Abstract: An improved bolt and bolt carrier with integral gas key having an extension nozzle threadedly secured and pinned to the gas key for use with a direct gas operated firearm is provided. The extension nozzle is designed to receive a portion of the host firearms gas operating system. The firing pin retaining pin is oriented so as to expose its widest profile to the firing pins annular flange, increasing its service life. The bolt has a plurality of lugs extending from its forward end and an extractor recess. The extractor recess is constructed to accommodate an enlarged extractor claw while not undercutting the bolt lugs adjacent thereto. The extractor engages approximately 57% more of a seated ammunition cartridges rim as compared to some prior art AR15/M16 type extractors used with automatic firearms chambered in 6.8 SPC. The result is an improved bolt and bolt carrier which provides for increased operational reliability.

Abstract: A recoil mechanism for an auto-loading firearm, having a gas-operated action bar assembly. One or more compression springs are used, mounted on associated retaining rods contained in a stationary orientation on the firearm. The springs are linked to the firearm's gas system at one end, and bear against stops affixed to ends of the spring retaining rods. The entire mechanism is contained within a forward grip mounted on the firearm, the grip optionally being provided with mounting rails.

Abstract: In various embodiments, a firearm assembly devices, systems and methods are provided. The firearm assembly can comprise a barrel and a chamber comprising a channel. The chamber may have a first length. The chamber may comprise an internal wall defining an internal cavity. The chamber can also couple to the barrel. The channel can be defined in the internal wall of the chamber. The channel may have a second length that is shorter than the first length. In various embodiments, the firearm assembly may be a component of a rotating bolt firearm. In various embodiments, internal cavity of the firearm assembly has a profile configured to receive a cartridge. The devices systems and methods described herein reduce common rotating bolt firearm failure modes by encouraging case ejection, compression, and/or contraction.

Abstract: A buttstock assembly configured to work in conjunction with a compact buffer assembly consisting of a buffer tube, spring and bolt carrier with an integral buffer is provided. The buttstock assembly, buffer tube and bolt carrier are configured to work with AR15/M16 type firearms and their derivatives. By incorporating the buffer onto the bolt carrier, which is used in conjunction with a buffer tube of reduced length, the overall length of the host firearm is reduced by approximately 3.2 inches. No permanent modification need be made to the host firearm in order to utilize the compact buffer assembly and buttstock assembly disclosed herein.

Abstract: An adjustable firearm gas block has a gas channel intersected by a threaded bore. A set screw with longitudinal slots is driven through the bore until it enters and constricts the gas channel. A second bore, parallel to the first bore, is connected to the first bore by a passage. A spring and a detent plunger having a slanted notch are inserted in the second bore with a bearing located in the slanted notch and passage. When the detent plunger is in a resting position, it presses the bearing into a longitudinal slot, preventing the set screw from turning. When the detent plunger is urged away from the resting position, the bearing disengages the longitudinal slot, traveling into the slanted notch and allowing the set screw to rotate, thereby adjusting the gas pressure emitted by the gas block.

Abstract: A gas-operated semi-automatic rifle having a barrel group, a receiver group, a bolt group, a stock group, a trigger group, and a magazine group. The barrel group includes a gas-operated operating rod, the operating rod further including a follower rod, the operating rod being biased away from the follower rod. The receiver group includes a receiver body. A cavity is formed in a forward portion of the receiver body, the cavity being sized and shaped to receive and movably retain a proximal end of the follower rod.