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.

A handguard for attachment to a standard AR-pattern firearm upper receiver. A barrel nut has a substantially cylindrical outer surface with an annular groove. A handguard sleeve has an end opening configured to slide over the outer surface of the barrel nut, a channel with a bottom guide surface, and a substantially transverse cross bore positioned to at least partially intersect the end opening to align with the annular groove when the handguard sleeve is positioned on the barrel nut. A pair of wedge members are sized to be received in the channel and connected by at least one wedge fastener configured to adjustably move the wedge members together. When the barrel nut is attached to an upper receiver, the handguard sleeve is attached to the upper receiver by sliding the end opening over the barrel nut and inserting a cross bolt fastener in the cross bore and a portion of the annular groove. The wedge members are pulled together by adjusting the wedge fastener, compressing them between the barrel nut and handguard sleeve.

A firearm handguard assembly system is disclosed. The system comprises a handguard including at least four apertures, a barrel nut having a first threaded end and a second smooth end, the threaded end coupled to the handguard, and an index block including at least four apertures, the index block coupled to the handguard by at least four screws, each screw having a head and a tip, the tip threaded through: one of the at least four apertures on the index block, and one of the at least four apertures on the handguard.

A two-piece barrel nut includes an internal nut with an externally threaded portion on one end and a plurality of engageable members on the opposite end, and an external nut with an internally threaded portion on one end that receives the externally threaded portion of the internal nut and one or more receptacles on the other end that each may receive a fastener that engages at least one of the plurality of engageable members on the internal nut to lock the external nut to the internal nut. A method for using the barrel nut to attach a barrel to a firearm is also disclosed.

A handguard for attachment to a standard AR-pattern firearm upper receiver. A barrel nut has a substantially cylindrical outer surface with an annular groove. A handguard sleeve has an end opening configured to slide over the outer surface of the barrel nut, a channel with a bottom guide surface, and a substantially transverse cross bore positioned to at least partially intersect the end opening to align with the annular groove when the handguard sleeve is positioned on the barrel nut. A pair of wedge members are sized to be received in the channel and connected by at least one wedge fastener configured to adjustably move the wedge members together. When the barrel nut is attached to an upper receiver, the handguard sleeve is attached to the upper receiver by sliding the end opening over the barrel nut and inserting a cross bolt fastener in the cross bore and a portion of the annular groove. The wedge members are pulled together by adjusting the wedge fastener, compressing them between the barrel nut and handguard sleeve.

A blocking member which mounts to a semi-automatic handgun provides for a face plate that prevents the gun slide from a cocked gun from being immobilized by pressure applied to the front of the muzzle.

An automatic rifle (10) includes a receiver (12), a bolt assembly (110), a trigger mechanism (106), a buttstock assembly (100), a barrel assembly (104), and a grip assembly (102). The receiver (12) is characterized by being a unitary body that houses the bolt assembly (110) and the trigger mechanism (106), and the receiver (12) is configured for the connection thereto of the buttstock assembly (100), the barrel assembly (104), and the grip assembly (102).

A gun body includes a gun body side connection portion, a barrel includes a barrel side connection portion, and the gun body side connection portion and the barrel side connection portion are connected to each other by an insertion structure. The gun body side connection portion includes an inner peripheral surface which is formed inward from a connection opening, the barrel side connection portion includes an outer peripheral surface, at least one of the inner peripheral surface and the outer peripheral surface is formed in a tapered shape, and the other of the inner peripheral surface and the outer peripheral surface is formed in a shape which is movable along the tapered shape. The gun body side connection portion and the barrel side connection portion are drawn in a direction along a center line by coupling means, the inner peripheral surface or the outer peripheral surface having the tapered shape and the movable shape are fitted to each other, and the barrel is centered.

A gas operated firearm includes a barrel with an integrally formed gas block as one piece with the barrel. A barrel nut is assembled over the integral barrel and gas block, securing the rear barrel end to a firearm receiver. Gas tube or piston assembly and field replacement are enhanced, along with accommodation of increased size barrels and integral muzzle end devices, no longer limited by internal dimensions of separately added gas blocks.

A two-piece barrel nut includes an internal nut with an externally threaded portion on one end and a plurality of engageable members on the opposite end, and an external nut with an internally threaded portion on one end that receives the externally threaded portion of the internal nut and one or more receptacles on the other end that each may receive a fastener that engages at least one of the plurality of engageable members on the internal nut to lock the external nut to the internal nut. A method for using the barrel nut to attach a barrel to a firearm is also disclosed.