Abstract: A rifle receiver arrangement including a hollow chamber with a silt to receive an end of a rifle barrel. A slit opening/closing arrangement including an abutment member to abut against a rotatable bolt once the rotatable bolt is rotated in a second direction beyond a first open position such that upon abutment between the rotatable bolt and the abutment member, further rotation of the rotatable bolt in the second direction increases the gap of the slit of the hollow chamber to provide an extended open position to allow the end of the rifle barrel to be accepted less restrictively into the hollow chamber.

Abstract: A free-floating rifle rail and barrel locking system that provides a barrel assembly and rail assembly, which is detachable from the main body of a rifle without tools. This is advantageous for quick field breakdown and/or rifle modification. The user has the option to disassemble the rifle for easy transport, to change barrel length, to change barrel caliber or change rail configurations. The rails are free-floating, meaning the rails do not come in contact with the barrel and thus do not impact the precision of the rifle.

Abstract: A apparatus implementable on a firearm includes a handguard assembly which is configured to at least partially surround a barrel of the firearm when the handguard is installed on the firearm. The handguard includes at least first and second physical features such that: (a) the first physical feature is configured to accommodate mounting of an accessory of the firearm on the handguard, and (b) the second physical feature is configured to secure a cable of the accessory onto the handguard.

Abstract: A free-floating rifle rail and barrel locking system that provides a barrel assembly and rail assembly, which is detachable from the main body of a rifle without tools. This is advantageous for quick field breakdown and/or rifle modification. The user has the option to disassemble the rifle for easy transport, to change barrel length, to change barrel caliber or change rail configurations. The rails are free-floating, meaning the rails do not come in contact with the barrel and thus do not impact the precision of the rifle.

Abstract: The modular upper receiver assembly for firearms is an adapter allowing interchanging of barrels of different calibers to attach to an upper receiver assembly. The adapter assembly serves to provide a quick changeover coupling means for connecting an assortment of barrels of different calibers and lengths to the receiver. The coupling includes a barrel retaining bushing and adapter pair with threaded surfaces on the receiver for a threaded engagement, reinforced with threaded fastener compression for improved rigidity.

Abstract: A device implementable on a firearm includes a monolithic upper receiver, comprising an upper receiver portion and a handguard portion, which is configured to accommodate non-proprietary barrel assemblies dimensioned according to United States military standard (mil-spec) barrel assembly dimensions and non-proprietary bolt carrier groups (BCGs) dimensioned according to mil-spec BCG dimensions. The device also includes a charging handle assembly configured to be coupled to an operating rod of a gas system of the firearm and forward of a BCG of the firearm. The device further includes a barrel locking system including a locking plate and a locking screw. When the locking screw is screwed into a threaded hole on the locking plate, the locking plate engages with a side of a barrel extension of the barrel assembly in a radial directions perpendicular to a longitudinal axis of the barrel assembly.

Abstract: An upper receiver assembly includes an outer member with an upper rail and an inner member with at least one of a pivot pin lug and a takedown pin lug. The inner member is disposed at least partially inside the outer member. The outer member includes an ejection port, and the inner member includes an ejection port. The ejection port of the inner member is at least partially aligned with the ejection port of the outer member.

Abstract: An interchangeable barrel system for a firearm includes one or more barrels each having an outer surface, and an inner surface defining a longitudinal bore open between a muzzle end and an action end. The action end has a threaded portion that includes one or more tangential notches formed partially therethrough. A receiver includes one or two threaded adjustment bolt apertures that tangentially intersect a barrel port. In use, with the action end of one of the barrels threadedly engaged with the barrel port and manually tightened to align one of the threaded adjustment bolt apertures with one of the notches, an adjustment bolt is tightened to contact an end of the notch to apply a tangential force to the barrel to further tighten the barrel within the receiver and to provide a desired headspace between the action end of the barrel and a bolt of the firearm.

Abstract: A rotating bolt firearm may be configured to fire a .308 cartridge. However, the firearm may have a reduced weight in comparison to standard .308 rifles. The firearm may have many components typically used in a .223 rifle. The firearm may include a barrel extension with an extractor gap, which allows a .308 bolt to fit within a .223 sized barrel extension. The firearm may comprise an elongated magazine well in comparison to a .223 mil-spec rifle. The firearm may weigh less than 6.8 pounds with a 16 inch barrel, or less than 6.3 pounds with a 10.5 inch barrel.

Abstract: A free-floating rifle rail and barrel locking system that provides a barrel assembly and rail assembly, which is detachable from the main body of a rifle without tools. This is advantageous for quick field breakdown and/or rifle modification. The user has the option to disassemble the rifle for easy transport, to change barrel length, to change barrel caliber or change rail configurations. The rails are free-floating, meaning the rails do not come in contact with the barrel and thus do not impact the precision of the rifle.

Abstract: A barrel mounting system to mount a barrel to a barrel mount of a firearm body includes a mount receiver secured to the barrel mount. The mount receiver includes axial channels and receiver threads disposed on an interior surface. The system further includes a barrel sleeve disposed around the barrel proximal to the proximal end of the barrel. The barrel sleeve includes sleeve threads disposed near a proximal end on an exterior surface and sized to slide through the axial channels and, when rotated, to engage the receiver threads. The system further includes a barrel collar disposed around the barrel and secured to the barrel and to limit the axial position of the barrel sleeve.

Abstract: A firearm configured for disassembly into stock, and receiver and barrel assemblies. Stock-receiver and receiver-barrel mounting assemblies facilitate assembling and disassembling the firearm. Modified components are adapted for placement on standard firearms and enable expedited assembly and disassembly. A firearm assembly method is also disclosed.

Abstract: A barrel mounting system for a firearm includes a longitudinal axis, a receiver, and a barrel detachably coupled to the receiver by upper and lower barrel mounting features above and below the barrel bore centerline. The lower mounting feature may comprise a clamping block compressing a lower breech end portion of the barrel against the receiver. In one embodiment, a pair of lower securement fasteners extend through the clamping block and threadably engage the receiver to draw the block into engagement with the receiver. The upper mounting feature may comprise a securement fastener compressing an upper breech end portion of the barrel against the receiver. The upper and lower mounting features form a triangular bolting pattern and balance moment forces created by the compressive forces of coupling the barrel to receiver with the fasteners.

Abstract: There is a multi-caliber weapon system. The multi-caliber weapon system comprises: a frame body, with a front body portion, a middle body portion, and a rear body portion, and including: a plurality of frame flanges, each frame flange being coupled to an interior of the frame body and extending upwardly therefrom; a barrel, removably coupled to the front body portion of the frame body, including: a plurality of barrel rings, each barrel ring being disposed around a circumference of the barrel and spaced along a length of the barrel, wherein the barrel rings are disposed on the frame flanges; a chamber, removably coupled to the middle body portion of the frame body, and removably coupled to the barrel; and a bolt, removably coupled to rear body portion of the frame body, removably coupled to the chamber, and including: a bolt face, removably coupled to a front bolt portion.

Abstract: A barrel extension usable with a firearm and a firearm having a barrel extension is disclosed. The barrel extension may include a barrel extension body extending along a barrel extension central axis between a barrel interface end. The barrel interface end may be configured to be connected to a barrel and the bolt receiving end may be configured to selectively receive a rotatable bolt of the firearm. The barrel extension may further include a plurality of barrel extension lugs at the bolt receiving end having bolt lug receiving openings therebetween, wherein each of the plurality of barrel extension lugs has a lug inner surface that is a first distance from the central axis, and each of the plurality of receiving openings have a receiving opening inner surface that is a second distance from the central axis.

Abstract: A firearm assembly including a receiver, a barrel, a locking block and a slide configured to provide rapid changing of a barrel of a handgun wherein the barrel may be for an alternate caliber round of ammunition. The locking block is configured to be secured within the receiver and includes an upper surface that has front rise member, a rear rise member and a valley intermediate thereto. The upper surface of the locking block is mateably shaped with the second portion of the barrel, in particular the lower portion thereof. The lower portion includes a front shoulder member, a rear shoulder member and a notch formed therebetween wherein the notch is configured to mateably engage the rear rise member of the locking block. The slide of the present invention includes a void intermediate the sidewall and the extractor housing. A shim is provided to be secured within the void.

Abstract: A modular precision rifle assembly 150 and a method for configuring rifle components allowing users to change barrel subassemblies 214 (i.e., for a replacement barrel for use with the same ammunition or a barrel configured for shooting a different ammunition caliber or type) includes three main components including a receiver subassembly 212, a barrel subassembly 214 and a forend subassembly 200. The receiver subassembly 212 includes a receiver housing 300 with a central lumen defining a plurality of substantially cylindrical contiguous cavities aligned along a central axis 300CA. The barrel assembly's bore is automatically forced into axial alignment with central axis 300CA when a user tightens a barrel coupler nut 500 against a barrel extension 400 due to the centering force generated when the extension's centering surface 410 bears against the coupler nut's cooperating centering surface 520.

Abstract: The invention relates to quick acting interfaces that allow for easier transportation and maintenance of precision rifles. Embodiments include an interface with an engaging segment and a receiving segment that engage one another and lock together. The engaging segment may have a series of connective bearings that fit into indentations inside the receiving segment. Embodiments allow a firearm to be modulated such that a barrel of the firearm may be disassembled without the need of any specialized equipment and reassembled without impacting the firearm's accuracy or reliability. Embodiments are scalable such that multiple interfaces can be used to adjust the total length of the firearm barrel.

Abstract: Firearms and barrel assemblies are provided herein that include a barrel assembly having a barrel having a proximal end and a distal end comprising a muzzle. The barrel also includes a chamber defined in the proximal end. The chamber includes a distal end and a proximal end. A bore extends distally from the distal end of the chamber. The bore defines a central axis of the barrel assembly. The barrel assembly also includes a barrel extension extending from the proximal end of the barrel. The barrel extension has a distal end and a proximal end. The barrel extension defines a bolt receiving recess in communication with the chamber. The barrel extension further has a barrel vent channel defined therein in communication with the bolt receiving recess. The barrel vent channel is defined in the barrel extension in a direction that is transverse to the central axis of the barrel assembly.

Abstract: Firearms and barrel assemblies are provided herein that include a barrel assembly having a barrel having a proximal end and a distal end comprising a muzzle. The barrel also includes a chamber defined in the proximal end. The chamber includes a distal end and a proximal end. A bore extends distally from the distal end of the chamber. The bore defines a central axis of the barrel assembly. The barrel assembly also includes a barrel extension extending from the proximal end of the barrel. The barrel extension has a distal end and a proximal end. The barrel extension defines a bolt receiving recess in communication with the chamber. The barrel extension further has a barrel vent channel defined therein in communication with the bolt receiving recess. The barrel vent channel is defined in the barrel extension in a direction that is transverse to the central axis of the barrel assembly.

Abstract: Example apparatus are disclosed for an adapter to attach at least one device to a self-loading firearm, the adapter comprising a barrel-side section and a receiver-side section adjacent the barrel-side section, wherein the barrel-side section and the receiver-side section extend in a longitudinal direction of the firearm, wherein one of the barrel-side section and the receiver-side section is securable to a retention device on a firearm barrel or a firearm receiver, and wherein the other of the barrel-side section and the receiver-side section can be moveably supported on the firearm receiver or the firearm barrel by a guide that allows for longitudinal movement of the receiver-side section or the barrel-side section with respect to the firearm.

Abstract: An upper receiver assembly for a firearm having an upper receiver with an integral barrel nut, a handguard assembly and a barrel nut assembly with a barrel and lock nut is provided. The barrel is received by the upper receiver and is secured directly to the upper receiver using the lock nut. The upper receiver also includes an integral handguard mounting member to which the handguard assembly may be directly attached. The upper receiver assembly allows the user to attach both the barrel and handguard assemblies directly to the upper receiver, independently of one another.

Abstract: A firearm suppressor assembly that includes a quick connect mounting methodology that allows the suppressor to be quickly and repeatably associated with the muzzle end of a firearm. In a preferred embodiment, the mounting methodology includes a plurality of lobes that facilitate less than 90 degree rotation between the muzzle of the firearm and the suppressor and provide a tactile indication of a secured engagement therebetween.

Abstract: An interchangeable barrel assembly for a firearm including a novel barrel and tool assembly which are used with a receiver having an open aft end. The tool assembly is configured to be inserted into the receiver open aft end so as to engage the aft end of the barrel. Torque applied to the tool assembly thereby transfers torque to the barrel without transferring forces to the action. This enables the same action to be used with different barrels and the barrel may be removed without removing the receiver or other components of the modular chassis or accessories mounted thereon. Additionally, standard torque may be applied to the barrel for connection to the receiver and firearm precision is maintained.

Abstract: Firearm handguard systems are disclosed, including rail alignment systems and anti-rotational firearm handguard systems. Also disclosed is a method of aligning a rail portion provided on an upper outer surface of a handguard using a handguard key that aligns the rail portion of the handguard with a rail portion of a firearm. Also disclosed is a firearm having a rail alignment system, and a handguard having a handguard key, wherein the handguard key is integrally formed with the handguard or is a modular handguard key configured to be removably attached to the handguard.

Abstract: A barrel nut assembly for use on a variety of firearms is provided. The assembly is made up of a barrel nut, generally cylindrical in shape with a threaded central bore, and an externally threaded locknut which is used in conjunction with the barrel nut to secure a barrel to a firearm upper receiver. The barrel nut has an integral bushing on its exterior constructed to support either the gas tube or piston of the host firearm's operating system. The barrel nut is configured so that it may be independently and non-rotationally held within a vice or other fixture during installation of the barrel and while the locknut is tightened to a preset torque to hold the barrel in place. The barrel nut assembly affords the user a method and apparatus that aligns a central bore in the bushing with the opening in the upper receiver that receives an operating system component of the firearm while the barrel nut is independent of the torque applied to the locknut to properly secure the barrel to the upper receiver.

Abstract: A barrel mounting system to mount a barrel to a barrel mount of a firearm body includes a mount receiver secured to the barrel mount. The mount receiver includes axial channels and receiver threads disposed on an interior surface. The system further includes a barrel sleeve disposed around the barrel proximal to the proximal end of the barrel. The barrel sleeve includes sleeve threads disposed near a proximal end on an exterior surface and sized to slide through the axial channels and, when rotated, to engage the receiver threads. The system further includes a barrel collar disposed around the barrel and secured to the barrel and to limit the axial position of the barrel sleeve.

Abstract: A rotating bolt firearm may be configured to fire a .308 cartridge. However, the firearm may have a reduced weight in comparison to standard .308 rifles. The firearm may have many components typically used in a .223 rifle. The firearm may include a barrel extension with an extractor gap, which allows a .308 bolt to fit within a .223 sized barrel extension. The firearm may comprise an elongated magazine well in comparison to a .223 mil-spec rifle. The firearm may weigh less than 6.8 pounds with a 16 inch barrel, or less than 6.3 pounds with a 10.5 inch barrel.

Abstract: A fixture for use with AR15/M16 type firearms is provided herein. The fixture is made up of several parts that when used in conjunction with one another mitigate the transfer of torque from the barrel nut to the firearms receiver during barrel installation. The fixture affords the user a method and apparatus that holds the barrel in alignment with the firearm receiver and secures the barrel against rotational movement during installation of a barrel nut or similar device. The fixture may be configured to work with the legacy AR15/M16 type barrel nut, as well as other designs as disclosed herein.

Abstract: A firearm includes a receiver, a forearm pivotally attached to a distal end of the receiver, and a barrel having a barrel extension. A proximal end of the barrel and the barrel extension are secured within the forearm such that the barrel and barrel extension are laterally pivotable with the forearm relative to the receiver between a first assembled position and a second folded position. The forearm, barrel, and barrel extension may be secured to the receiver in the first assembled position for use of the firearm, after which the firearm may be folded for storage and/or transportation.

Abstract: A modular precision rifle assembly 150 and a method for configuring rifle components allowing users to change barrel subassemblies 214 (i.e., for a replacement barrel for use with the same ammunition or a barrel configured for shooting a different ammunition caliber or type) includes three main components including a receiver subassembly 212, a barrel subassembly 214 and a forend subassembly 200. The receiver subassembly 212 includes a receiver housing 300 with a central lumen defining a plurality of substantially cylindrical contiguous cavities aligned along a central axis 300CA. The barrel assembly's bore is automatically forced into axial alignment with central axis 300CA when a user tightens a barrel coupler nut 500 against a barrel extension 400 due to the centering force generated when the extension's centering surface 410 bears against the coupler nut's cooperating centering surface 520.

Abstract: A firearm vise block can include a block body and an adjustment mechanism. The block body can include a first side structured and configured to be clamped between jaws of a bench vise, and a second side can be structured and configured to fit within an ammunition magazine well of a firearm. The second side can be adjustable between at least an insertion state and an expanded state. The adjustment mechanism can be structured and configured to selectively and reversibly move the second side between the insertion state and the expanded state.

Abstract: A rifle comprises a quad lock multicaliber receiver, a barrel extension, a bolt, and a projection engageable with the receiver. The barrel extension includes a cartridge chamber and is securable in an end of the receiver. The bolt is slideable in the receiver and engages a cartridge in the cartridge chamber during the firing phase. The projection comprises locking bars extending through the receiver, and is moveable between locked and unlocked positions to allow for securing and removing of the barrel extension, respectively. Positioning bars are disposed on either side of the receiver split parallel to its longitudinal axis. The locking bars are disposed between these positioning bars and the barrel extension such that when the positioning bars are urged toward each other the receiver split is closed and the positioning bars urge the locking bars toward and into locking grooves to secure the barrel extension in the receiver.

Abstract: Firearms, and components of firearms, improve shooting accuracy, due to increased coaxial alignment between the receiver and the barrel of the firearm. The outer surface of the barrel and the receiver inner surface feature extremely-tight-tolerance/press-fit mating of one or more outer axial mating surfaces of the barrel with one or more axial portions of the receiver inner surface. The extremely-tight-tolerance/press-fit axial mating surfaces may be distal of, proximal of, in-between, and/or otherwise outside and separate from the threads or conventional connection means for connecting the barrel to the receiver.

Abstract: Provided is a side charging handle system for an AR-pattern firearm with an upper receiver having an internal longitudinal bore for receiving a bolt carrier assembly for longitudinal reciprocation therein, a side longitudinal guide slot, and a side charging handle having an engagement pin extending through guide slot to engage the bolt carrier assembly. Also provided is a compact bolt carrier system including an upper receiver having an internal longitudinal bore for receiving a bolt carrier assembly for longitudinal reciprocation therein and a longitudinal recoil spring guide channel positioned above the internal longitudinal bore. The bolt carrier assembly has a bolt carrier body configured in length to reciprocate substantially entirely within the upper receiver and has a top lug extending into the recoil spring guide channel. A recoil spring is in the recoil spring guide channel.

Abstract: Firearms and barrel assemblies are provided herein that include a barrel assembly having a barrel having a proximal end and a distal end comprising a muzzle. The barrel also includes a chamber defined in the proximal end. The chamber includes a distal end and a proximal end. A bore extends distally from the distal end of the chamber. The bore defines a central axis of the barrel assembly. The barrel assembly also includes a barrel extension extending from the proximal end of the barrel. The barrel extension has a distal end and a proximal end. The barrel extension defines a bolt receiving recess in communication with the chamber. The barrel extension further has a barrel vent channel defined therein in communication with the bolt receiving recess. The barrel vent channel is defined in the barrel extension in a direction that is transverse to the central axis of the barrel assembly.

Abstract: A gun includes a bolt, a bolt stop member and a shock-absorption device. The bolt is movable forward or backward in a gun body, accumulates a pressure of a buffer spring while moving backward according to manipulation of the gun, and moves forward by releasing the accumulated pressure. The bolt stop member stops the bolt moving forward. The shock-absorption device includes a shock-absorption link which engages with a shock-absorption shaft which acts on the bolt stop member to absorb an impact force applied to the bolt stop member by the engagement of the bolt and the bolt stop portion.

Abstract: Pistols have a body having a grip, the body having a trigger guard, the body having an upper slide interface surface defining a slide interface plane, the body having a first mounting facility at a forward end below the slide interface plane and at a level above at least a portion of the trigger guard, a dust cover having a rear end having a second mounting facility adapted to removably dock with the first mounting facility in an attached position, the dust cover defining an upper surface in the slide interface plane when the dust cover is in the attached position, and the first mounting facility and second mounting facility comprising a sliding interface. The sliding interface may be a dovetail feature.

Abstract: The present invention relates to a gun with a removable barrel, the barrel having a mounting rail connected to it and extending in the direction of the longitudinal barrel axis A, the barrel being connected to the system housing by means of a receptacle on the system housing, the receptacle being tubular at least partially in the direction of the longitudinal barrel axis A and the corresponding inner tube diameter dl being adapted to the outer circumference of the barrel, so that the barrel can be introduced into the receptacle in the direction of the longitudinal barrel axis A when the barrel is mounted on the system housing, and wherein the receptacle has a recess of the tube circumference which extends in the direction of the longitudinal barrel axis A, wherein the barrel is fixed axially with respect to the longitudinal barrel axis A by at least one connecting element and is fixed with respect to rotation at least in that the mounting rail extends in its longitudinal direction at least partially within th

Abstract: A rifle comprises a quad lock multicaliber receiver, a barrel extension, a bolt, and a projection engageable with the receiver. The barrel extension includes a cartridge chamber and is securable in an end of the receiver. The bolt is slideable in the receiver and engages a cartridge in the cartridge chamber during the firing phase. The projection comprises locking bars extending through the receiver, and is moveable between locked and unlocked positions to allow for securing and removing of the barrel extension, respectively. Positioning bars are disposed on either side of the receiver split parallel to its longitudinal axis. The locking bars are disposed between these positioning bars and the barrel extension such that when the positioning bars are urged toward each other the receiver split is closed and the positioning bars urge the locking bars toward and into locking grooves to secure the barrel extension in the receiver.

Abstract: An anti-rotation handguard system, including a barrel nut having a barrel nut aperture formed therethrough, along a longitudinal axis of the barrel nut, wherein the barrel nut includes a registration groove defined around the outer periphery of the barrel nut; and an anti-rotation ring having a barrel nut aperture formed therethrough, wherein the anti-rotation ring further comprises a first anti-rotation tab extending from the anti-rotation ring, wherein the first anti-rotation tab is formed so as to be received within a gas tube channel of a handguard, and wherein the anti-rotation ring further comprises a second anti-rotation tab extending from the anti-rotation ring, wherein the second anti-rotation tab is formed so as to be received within at least a portion of a compression/registration slot of the handguard.

Abstract: A firearm barrel tray having a barrel channel and a firearm accessory mounting interface, wherein the firearm barrel tray is configured to be attached to a firearm stock such that the barrel channel sits on a first side of the firearm stock and the firearm accessory mounting interface is configured to align with a recess on a second side of the firearm stock.

Abstract: An example firearm with a short overall length and improved storage compactness comprises a forward takedown subassembly comprising a barrel, a trigger control mechanism configured to provide an electrical trigger control signal, and a signal transmitter electrically coupled to the trigger control mechanism, and further comprises a rearward takedown subassembly separable from the forward takedown subassembly and comprising a stock, a receiver comprising an electrically controlled firing mechanism, and a signal receiver electrically coupled to the firing mechanism. A takedown mechanism has first and second portions fixedly coupled to the forward takedown subassembly and the rearward takedown subassembly, respectively, and is configured to repeatably couple the forward takedown subassembly to the rearward takedown subassembly.

Abstract: A device and method for stabilizing a rifle scope that employs a pocket cut in the bottom of a scope base (picatinny rail) that precisely mates with a key formed on the top of a recoil lug, such that when the scope base is attached to the rifle's action receiver and mated with the lug's key, the lug holds the barrel and the scope base locked in tandem so that they move exactly together during recoil events or any vibrations experienced by the rifle.

Abstract: The present invention is a semi-automatic pistol receiver assembly comprising multiple removable parts rather than single piece construction normally used in semi-automatic pistols.

Abstract: A conversion kit for a firearm of the type having a removable component is disclosed. The conversion kit includes a chamber piece having a coupling end, and a muzzle piece of a conversion barrel having a coupling end configured to be secured to the coupling end of the chamber piece and an engagement end. The engagement end is configured to mate with the removable component such that manipulation of the removable component causes the coupling end of the muzzle piece of the conversion barrel to be secured to the coupling end of the chamber piece.

Abstract: A breakdown adapter having a retainer. The retainer has a left retainer and a right retainer. The left retainer has a left engaging means and a left retaining means. The right retainer has a right engaging means and a right retaining means. The left engaging means has two or more left protrusions. The right engaging means has two or more right protrusions. The fastener is configured to secure left engaging means to the right engaging means.

Abstract: A receiver having an integral stock connector component that extends along the receiver; two extension rod/rail apertures formed through the integral stock connector component, wherein each extension rod/rail aperture is formed so as to slidably receive an extension rod/rail extending from a buttstock, such that each extension rod/rail is slidably movable within one of the extension rod/rail apertures; wherein each extension rod/rail comprises a rod channel and two or more rod dimples/detents formed along the rod channel; and a latch that is movable between an engaged position and a disengaged position, wherein when the latch is in the engaged position, a protrusion portion urges latch elements into the rod/rail apertures a distance that seats the latch elements into the rod dimples/detents, and wherein when the latch is in the disengaged position, the protrusion portion allows the latch elements to retract from the rod dimples/detents and into the rod channels.

Abstract: A gun device allowing replacement of barrels with different sizes, having a gun body, one end of the gun body has an opening. The opening outer edge has a threading and a positioning slot. The gun body connects with a first size barrel by connecting the threading with a lock. The gun device further comprising: a guide adapter, a second size barrel and a barrel key. The guide adapter has a positioning body, a projecting part, and a first groove, the projecting part alignment connects with the positioning slot. The second size barrel has a second groove, the first groove corresponding with the second groove.

Abstract: An M240 machine gun barrel assembly with a barrel with a muzzle end at the distal end of the barrel and a breach end at the proximal end of the barrel; a handle connector connecting the barrel to a handle assembly; and the handle assembly having a free end and a connected end, the connected end operably connected to the handle connector; the handle assembly operable between a first position with the free end of the handle assembly pointing proximally and a second position with the free end of the handle assembly pointing distally.