Abstract: Embodiments of the disclosure relate to semi-automatic, automatic, and bolt-action firearms and components for such firearms.

Abstract: An advanced gas piston operating system for Armalite Rifle (AR) and Armalite Rifle variants. The advanced gas piston system may include a barrel having a gas port formed through the barrel wall, a gas block assembly, a gas piston assembly, and upper receiver assembly, a sending block, rack and gear assembly, and a bolt carrier assembly with an attached rack. In such a system, a portion of the combustion gases from a fired projectile travel through a gas port in the barrel into a gas block assembly which drives a piston forward which compresses a main spring on an attached rod. The opposite end of the rod is attached to a sending block rack and gear assembly with the gear rotatably engaged with the teeth of another rack that is attached to the bolt carrier assembly. As the gas piston assembly moves forward, the bolt carrier assembly moves rearward until the main spring is fully compressed. Decompression of the main spring returns bolt carrier assembly forward loading the next round into the chamber.

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 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: The present invention is directed to a polymer training rifle which may include a modular receiver portion, a simulated barrel nut, one or more interchangeable modular barrels, and a receiver extension tube. Selected parts and tactical accessories may be connected to the rifle training system to provide a customized training rifle. The modular receiver may include a magazine well that receives an actual magazine or an inert replica magazine. The receiver portion also may include a functional magazine catch assembly which allows a trainee to selectively secure and release a magazine from the magazine well. The one or more modular barrels, modular receiver portion, and inert replica magazine may each include a metal core to allow for detection by security screening equipment.

Abstract: A gas operating system for a firearm renders the firearm capable of firing a wide range of shot loads by passively or automatically compensating for different shot loads. The firearm includes a plurality of ports formed in the firearm barrel, and corresponding ports formed in a gas block of the gas operating system. The ports tap gases generated during firing which are used to cycle the firearm. When firing different cartridge loads, differing combinations of the ports are selectively at least partially blocked or otherwise obstructed by the cartridge casing according to the size of the cartridge. Additionally, the gas operating system includes compensating gas pistons with internal relief valves that can bleed off excess gas to compensate for larger shot loads regardless of the size of the cartridge.

Abstract: A semi-automatic or automatic rifle comprising a barrel attached to and upper receiver and including a compressible bolt carrier extension system. The compressible bolt carrier extension system includes a bolt carrier, an extension spring, two pins, and a reciprocation bolt carrier extension piece. As a whole, the compressible bolt carrier extension system makes possible the use of elongated upper and lower receivers to be used for chambering long-action or other center fire cartridges for use with AR rifles such as the M-16, and M4 etc., eliminating the need for any buffer or buffer tubes other than those commercially available. A further advantage of the compressible bolt carrier extension system is the reduction of felt recoil as the system fully loads during the recoil stroke as it pushes against the buffer absorbing additional recoil energy. The system can be incorporated into firearms using a variety of cartridges.

Abstract: The embodiments described herein relate to a sleeve piston for operating the bolt carrier of an auto-loading firearm. The sleeve piston can comprise a monolithic sleeve piston or it can comprise two or more sleeve-piston parts, thereby evenly distributing the reciprocating mass of an auto-loading firearm about its barrel and minimizing muzzle rise when fired. The sleeve piston can be coupled to the bolt carrier by two or more operating rods, thereby reducing the tipping force experienced by the bolt carrier during firearm operation. The sleeve piston can reciprocate in or on a gas block coupled to the barrel, and the sleeve piston can be removed by sliding it forward and off the end of the barrel. The embodiments of the present invention can thus provide a balanced and compact operating mechanism that is ideally suited for rifles, carbines, and personal-defense weapons.

Abstract: A combined retrofit direct drive gas piston system, for use with M-16 rifle and other appropriated platforms, operating in conjunction with a frontal actuated, ambidextrous, non reciprocating charging system, working in tandem with other existing charging handle systems. The device, conceived to be installed in said rifles in an effortless manner by coupling supporting components with the receiver and the barrel without performing any machining operations. The artifact partially comprises affixing supports, a structural tube to constrain and hold the components, a securing frontal gas block, a regulated direct gas piston system including an independent push bar with alignment rings, springs, and freely displacing part with projections connecting with the exterior handle or hand guard actuator. By enabling to use the extended firer's supporting hand for charging, said artifact solves complicated ergonomic maneuvers required to charge the original M-16.

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: A rifle in a bullpup configuration is provided, comprising a receiver having a trigger assembly and a magazine well, and a barrel having a barrel extension attached to the receiver. A gas assist system is attached to the barrel, including a gas housing surrounding the barrel and having an annular expansion chamber, and an annular gas piston slidably disposed within the gas housing. A thrust block is in contact with the gas piston, wherein the thrust block is slidably disposed along one or more action guide members. A rigid slide member extends from the thrust block and behind the trigger assembly. A bolt carrier and bolt are attached to the second end of the slide member and slidably disposed along one or more bolt guide members.

Abstract: A gas operating system for a firearm includes a gas block, a barrel nut that maintains the gas block at a predetermined axial position on a barrel of the firearm, a member that is movable with respect to the gas block axially with respect to the barrel in response to pressure exerted by expanding propellant gases conveyed thereto by the gas block and a mechanical linkage receiving a force form the member urging it in an axial direction of the barrel and coupled with a loading and ejection mechanism of the firearm to convey the force thereto for operating the loading and ejection mechanism. Various embodiments of gas block assemblies and operating rods for gas operating systems for firearms are provided.

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 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 rifle in a bullpup configuration is provided, comprising a receiver having a trigger assembly and a magazine well, and a barrel having a barrel extension attached to the receiver. A gas assist system is attached to the barrel, including a gas housing surrounding the barrel and having an annular expansion chamber, and an annular gas piston slidably disposed within the gas housing. A thrust block is in contact with the gas piston, wherein the thrust block is slidably disposed along one or more action guide members. A rigid slide member extends from the thrust block and behind the trigger assembly. A bolt carrier and bolt are attached to the second end of the slide member and slidably disposed along one or more bolt guide members.

Abstract: An indirect gas operating system for a semi-automatic or automatic rifle is provided, the indirect gas operating system having: a gas block secured to the rifle; a barrel secured to the rifle; a bolt carrier slidably received within a receiver of the rifle; a means for moving the bolt carrier within the receiver using gases discharged into a bore of the barrel of the rifle, wherein the means for moving is removably secured to the gas block such that the means for moving can be removed from the rifle through a forward end of the gas block without removing the gas block from the rifle; and an externally threaded barrel nut for securing the barrel to the receiver.

Abstract: An annular piston system for a firearm comprises a barrel, a gas block assembly, a piston, and a spring. The barrel has multiple sections lengthwise, one of the sections having at least one gas port hole to vent gas from the barrel. The gas block assembly is disposed annularly around the barrel and is adjustable to control an amount of gas flowing out of the barrel through the at least one gas port hole. The piston is disposed annularly around the barrel and can move longitudinally along the barrel in response to being pushed by the gas flowing out of the barrel. The spring is disposed annularly around the third section of the barrel and coupled to the piston. The spring limits a distance that the piston can move longitudinally along the barrel when the piston is pushed to move by the gas flowing out of the barrel.

Abstract: This application discloses a firearm gas system that includes a gas block that defines a gas port and a passage that receives a gas tube and an orifice plate that defines at least two orifices, where the orifice plate is positioned between a gas port in the barrel and the gas port on the gas block and where the orifice plate is movable with respect to the gas ports in the barrel and gas block to selectively position one of the orifices between the gas ports in the barrel and gas block where the orifices in the orifice plate have different orifice sizes.

Abstract: The embodiments described herein relate generally to a sleeve piston for operating the bolt carrier of a firearm. The sleeve piston can comprise a monolithic sleeve piston or it can comprise two or more sleeve-piston parts, thereby evenly distributing the reciprocating mass of an auto-loading firearm about its barrel, minimizing muzzle rise. The sleeve piston can further be coupled to the bolt carrier by two or more operating rods, thereby reducing the tipping force or off-axis torque experienced by the bolt carrier during firearm operation. The sleeve piston can also reciprocate in a sleeve gas block coupled to a barrel, thereby helping to transfer heat away from the barrel. The sleeve piston embodiments of the present invention provide a balanced and compact operating mechanism that is ideally suited for rifles, carbines, and personal-defense weapons.

Abstract: An annular piston system for a firearm comprises a barrel, a gas block assembly, a piston, and a spring. The barrel has multiple sections lengthwise, one of the sections having at least one gas port hole to vent gas from the barrel. The gas block assembly is disposed annularly around the barrel and is adjustable to control an amount of gas flowing out of the barrel through the at least one gas port hole. The piston is disposed annularly around the barrel and can move longitudinally along the barrel in response to being pushed by the gas flowing out of the barrel. The spring is disposed annularly around the third section of the barrel and coupled to the piston. The spring limits a distance that the piston can move longitudinally along the barrel when the piston is pushed to move by the gas flowing out of the barrel.

Abstract: An indirect gas operating system for a semi-automatic or automatic rifle is provided, the indirect gas operating system having: a sleeve removably secured to a forward end of a gas block of the rifle; a piston slidably received within the gas block, wherein the gas block and the sleeve fluidly couple the piston to a bore of a barrel of the rifle; wherein an increase in pressure in the bore of the rifle causes the piston to move away from the sleeve; and wherein the sleeve and the piston are each capable of being removed from the rifle through the forward end of the gas block.

Abstract: A gas operated autoloading firearm having an improved bolt carrier. The gas piston system may include a barrel defining a longitudinally-extending bullet pathway, a gas block defining a piston bore, a passageway fluidly connecting the bore with the bullet pathway for diverting combustion gas to the bore upon discharging the firearm, and a piston slidably disposed in the bore for reciprocating movement. The piston actuates a reciprocating bolt assembly including a bolt carrier slidably received in a receiver. The bolt carrier includes supporting and guiding surfaces configured to reduce receiver wear and bolt carrier drag.

Abstract: A gas pressure mechanism that receives and supplies gas pressure to a semi or automatic shotgun during the shotgun's reloading operation. The gas pressure mechanism includes twin body members having a front cylinder in fluid communication with a rear cylinder. Each rear cylinder includes a rear gas port disposed in communication with the interior of the shotgun barrel such that gases of combustion is bled through the rear gas ports from the interior of the barrel to the interior of the rear cylinders. Similarly, each front cylinder includes a front gas port disposed in communication with the interior of the shotgun barrel at a location to effectively recoil and counter-recoil the shotgun's piston or breech bolt to its rear most position. The rear cylinders, are situated immediately in front of the shotgun's shell chamber such that the rear gas ports capture and receive the gas pressure developed immediately behind the shell load as it travels through the barrel after firing.

Abstract: A firearm including a barrel having a breech and a muzzle defining a length of the barrel is disclosed. The firearm includes a hand guard having a first end and a second end with a front sight is attached to at least one of the barrel adjacent the muzzle and the second end of the hand guard. A housing is coupled to the front sight and defines a chamber having a piston disposed therein and movable between static and displaced positions. A receiver is coupled to the first end and a bolt carrier is disposed within the receiver and moveable between firing and rearward positions. A carrier key is attached to the bolt carrier and moves concurrently with the bolt carrier and a rod is permanently affixed to the carrier key and extends to a distal end with the piston engaging the distal end when moving to the displaced position.

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 gas tappet system for use in an M16, M4, or AR-15 type rifle having a detachable piston eccentrically connected to an operating rod. A piston having a plenum therein and a releasably attached operating rod uses combustion or propellant gasses to move the piston in a long stroke, preventing damaging impulses to the bolt carrier and cycling rounds for automatic or semi-automatic fire. The operating rod, piston, cylinder, and mounting clamp permit easy installation on the rifle without any modification and can easily be removed for reinstallation of the original direct gas impingement system.

Abstract: A kit for modifying a bolt carrier group actuating apparatus of a firearm configured by its original manufacturer to have a gas-driven bolt carrier has a gas expansion assembly and an operating rod. The gas expansion assembly is configured for receiving combustion gases from an as-manufactured OEM gas block of a firearm and for facilitating expansion of the gases for generating a bolt carrier driving force. The operating rod is engagable between the gas expansion assembly and an operating rod engaging lug of a bolt carrier. The operating rod is configured to mechanically transmit the bolt carrier driving force to the operating rod engaging lug.

Abstract: A semi-automatic or automatic rifle is provided the rifle having: a receiver having a hand guard portion; a barrel having a bore, the bore removably connected to the receiver, the hand guard portion surrounding at least a portion of the barrel; a gas block having a forward end and a rearward end aligned with the barrel; a sleeve removably secured to the forward end of the gas block; a piston slidably received within the gas block, wherein the gas block and the sleeve fluidly couple the piston to the bore of the barrel; wherein an increase in pressure in the bore of the barrel causes the piston to move away from the sleeve; and wherein the sleeve and the piston are each capable of being removed from the rifle through the forward end of the gas block without removing the gas block from the rifle.

Abstract: A kit for modifying a bolt carrier group actuating apparatus of a firearm manufacturer-configured with a gas-driven bolt carrier comprises a gas expansion assembly, an operating rod driven bolt carrier and an operating rod. The gas expansion assembly is configured for receiving combustion gases from an as-manufactured OEM gas block of the firearm and for facilitating expansion of said gases for generating a bolt carrier driving force. The operating rod driven bolt carrier includes an operating rod engaging lug. The operating rod driven bolt carrier is configured for being operably engaged within an as-manufactured OEM receiver body of the firearm with the operating rod engaging lug located in a gas tube lug receiving portion of the as-manufactured OEM receiver body. The operating rod is engagable between the gas expansion assembly and the operating rod engaging lug.

Abstract: A direct drive retrofit system for use with an M-16 or AR-15 rifle for conversion from an impingement system comprising: a gas block, the gas block having a barrel bore and a gas plug bore; a gas plug, the gas plug being inserted into the gas plug bore from the muzzle end; a bolt carrier key, the bolt carrier key being configured to mount directly to a bolt carrier; a rod, the rod being manufactured from a single continuous material stock; and a biasing means; wherein, the rod can be uninstalled without removal of a hand guard or the gas block by extracting the gas plug from the gas plug bore from the muzzle end, the actuating means releasing the rod, the rod being freely extracted thereafter by a user in a single piece.

Abstract: A semi-automatic or automatic rifle is provided. The semi-automatic or automatic rifle includes a receiver having an integral hand guard portion, a barrel having a bore. The bore is removably connected to the receiver, the hand guard portion extending over and surrounding the barrel, an indirect gas operating system has a gas block and a piston. The gas block has a cylinder, the gas block is fitted to the barrel, the cylinder is in communication with the bore. The piston has a piston end and a striking end, the piston end is fitted to the cylinder and has a bolt carrier having a striking surface. When a cartridge is fired, gas displaces the piston end and causes the striking end to strike the striking surface displacing the bolt assembly, wherein, the cylinder and the piston are together removable as an assembly from the firearm without disassembly of the rifle.

Abstract: A firearm barrel assembly having a gun barrel with a muzzle opening on a distal end, a shroud coaxially surrounding at least a portion of the barrel, the shroud having a distal portion extending beyond the muzzle opening defining a shroud front region having a distal end portion, a proximal portion extending proximally from the muzzle opening defining an annular region between the barrel and shroud, the shroud front region and annular region in fluid communication with substantially no obstruction between the shroud front region and the annular region, and a front wall disposed at the distal end portion of the shroud. The wall has an opening to allow passage of a projectile fired from the firearm.

Abstract: A piston assembly is provided for a gas-operated firearm of the type having a chamber and a barrel. The piston assembly includes a gas expansion housing and a piston mounted within the gas expansion housing. An annular recess is formed in the outer wall of the piston to receive exhaust gases diverted from the barrel upon firing of the firearm. At least one longitudinally extending groove extends from the annual recess to the head of the piston and forms a pathway for diverting the exhaust gases to the head of the piston. During firing, pressurized gases are diverted into the annular recess and expand longitudinally from the annular recess to the piston head, whereupon the pressurized exhaust gas drives the gas piston rearwardly along the housing.

Abstract: An indirect gas operating system for an M4 type automatic or semi-automatic firearm. The indirect gas operating system has a gas block having a cylinder. The gas block is fitted to a barrel assembly having a bore with the cylinder in communication with the bore. A piston having a piston end and a striking end has the piston end fitted to the cylinder. A bolt assembly having a striking surface is provided. When a cartridge is fired, gas displaces the piston end and causes the striking end to strike the striking surface displacing the bolt assembly. The cylinder and the piston are together removable as an assembly from the firearm without removal of the gas block.

Abstract: A direct drive retrofit system for use with an M-16 or AR-15 rifle for conversion from an impingement system comprising: a gas block, the gas block having a barrel bore and a gas plug bore; a gas plug, the gas plug being inserted into the gas plug bore from the muzzle end; a bolt carrier key, the bolt carrier key being configured to mount directly to a bolt carrier; a rod, the rod being manufactured from a single continuous material stock; and a biasing means; wherein, the rod can be uninstalled without removal of a hand guard or the gas block by extracting the gas plug from the gas plug bore from the muzzle end, the actuating means releasing the rod, the rod being freely extracted thereafter by a user in a single piece.

Abstract: Methods and apparatus are described for gas cylinder components for use with a firearm with a barrel. The gas cylinder component includes a reception bore for receiving the barrel. Additionally, the gas cylinder component includes a torque-proof fixture that is under pre-stressing, wherein the torque-proof fixture comprises one or more bores tangential to the barrel further including a pin to create spring pinning action. Further, the gas cylinder component includes a foresight that is rotatable around an axis, and a demountable clamping device that secures at least one position of the foresight. The gas cylinder component is under spring pre-stressing and is torque proof on the barrel. Additionally, the gas cylinder component is to lock on the barrel. Further, the engagement of the gas cylinder component on the barrel is to substantially prevent the rotation of the gas cylinder apparatus relative to an axis of the barrel.

Abstract: An individual firearm with improved recock device comprising a casing (12), a barrel (13), a breech bolt (14), a breech bolt slide (15), wherein the barrel (13) has at least one hole (32), or gas bleeding port, communicating with a gas intake cylinder (19) which houses a piston gas intake assembly (20), which is connected to operating rods (31) integral to the breech bolt slide (15), comprises at least one first inertial spring (27, 27?) arranged between the breech bolt slide (15) and the gas intake cylinder (19), adapted for causing a variable, inertial and/or gas intake actuation.

Abstract: A direct drive retrofit system for use with an M-16 or AR-15 rifle for conversion from an impingement system comprising: a gas block, the gas block having a barrel bore and a gas plug bore; a gas plug, the gas plug being inserted into the gas plug bore from the muzzle end; a bolt carrier key, the bolt carrier key being configured to mount directly to a bolt carrier; a rod, the rod being manufactured from a single continuous material stock; and a biasing means; wherein, the rod can be uninstalled without removal of a hand guard or the gas block by extracting the gas plug from the gas plug bore from the muzzle end, the actuating means releasing the rod, the rod being freely extracted thereafter by a user in a single piece.

Abstract: A semi-automatic rifle includes a frame (2); a barrel (3); a sliding guide (9) mounted in the frame (2) and forming one piece with breech bolts (10) which make it possible to control the recocking and the locking of the rifle (1); an automatic recock device (12) includes a piston (13) mounted in a gas cylinder (14) whose chamber (15) is connected to the bore (7) of the barrel (3) via a vent hole (16), whereby the piston (13) makes contact with the head of a sliding guide (17) which is connected to the sliding guide (9) and which is mounted in a sliding manner on a guiding rod (19) which forms one piece with the frame (2) and which is mainly parallel to the axis of the barrel (3).

Abstract: A self-cleaning gas operating system for a firearm having a conventional bolt carrier assembly is disclosed comprising: a nozzle assembly having a nozzle in direct communication with a port on the muzzle; said nozzle assembly nested within a piston cup having a vent, a connecting rod operationally linking the piston cup to a spring loaded operating rod which is substantially co-axial to a bolt carrier key having a striking portion, said striking portion having a concave strike face in contact with said operating rod, wherein gas discharged from a fired cartridge displaces the piston cup and causes the operating rod to strike the strike face displacing the bolt assembly.

Abstract: A push rod operating system for an AR-15/M-16 rifle includes an AR-15/M-16 rifle having a barrel coupled to an upper receiver, a bolt carrier carried by the upper receiver, and a mechanical key coupled to the bolt carrier. A gas block is coupled to the barrel, the gas block having a bore therethough. A rod tube extends from the gas block in communication with the bore, toward the upper receiver. A gas plug has a gas chamber closing the bore of the gas block opposite the rod tube. A discharge gas pathway permits discharge gasses to enter the gas chamber from the barrel. A piston rod element is carried in the rod tube with a piston portion thereof reciprocally received within the bore of the gas block and movable between a first position abutting the gas plug to define an operating volume, and a second position. A push rod element is carried by the rod tube and engages the mechanical key and the piston rod element.

Abstract: A piston element, which has a piston element made of a single piece, one of the important parts of a gas operated shotgun enabling the shotgun to operate, and the piston rings assembled into the slots on the piston element. At least one female part connects with at least one male part, forming the piston element, in order to provide the piston element to be formed by screwing two parts to each other and positioning the piston ring between the same, and at least one sealing member positioned between the male and the female part.

Abstract: This is a gas-flow device for semiautomatic or automatic shotguns, which consists of a gas-flow cylinder, closed at the front part by a flange with gas discharge ports (17) around the ammunition magazine, opposite the cylinder, a circular valve (18) that moves axially for controlled opening and closing of the discharge ports. The valve is kept in the closed position by a pre-stressed spring (19) and it moves to the open position when the gas pressure in the expansion chamber increases beyond a set value.

Abstract: A low impulse firing attachment and companion ammunition for combination gas and recoil operated automatic weapons is comprised of a barrel insert and piston that provide the mechanism for containing the expanding propellant gases produced on firing. Such mechanism provides the required gas pressure at the gas port of the weapon to power the gas system. The barrel insert also allows the use of a sub-caliber piston for the propellant gases to act against. The gas pressure forces the barrel and piston apart, accelerating the recoiling mass rearward to provide recoil operation. The sub-caliber piston allows the use of the relatively high gas port pressure while limiting the peak force transmitted through the adapter. The blank and adapter provide the appropriate gas pressure at the gas port to power the gas system. The adapter also acts as a piston inside the barrel so that the gas pressure forces the barrel rearward, which provides the recoil operation.

Abstract: The invention concerns a gas operated shotgun made up of a barrel (11) a cylinder (12) attached to the barrel and a piston (13) moving in the cylinder and along the guide rod (16) between an advanced rest position and an active retracted control position for certain functional operations of the shotgun. The inside of the barrel communicates with the cylinder through at least one inlet (14) for of a part of the propulsion gasses due to the movement of the piston to the active retracted position. A protective flap (20) extends into the cylinder chamber towards the piston on the front of the same, which is placed in front of the gas entrance hole (14) in said cylinder chamber partially covering and protecting the guide rod (16) of the piston. The piston can also be furnished with a scraper (22) to clean the rod.

Abstract: This is a gas-flow device for semiautomatic or automatic shotguns, which consists of a gas-flow cylinder, closed at the front part by a flange with gas discharge ports (17) around the ammunition magazine, opposite the cylinder, a circular valve (18) that moves axially for controlled opening and closing of the discharge ports. The valve is kept in the closed position by a pre-stressed spring (19) and it moves to the open position when the gas pressure in the expansion chamber increases beyond a set value.