A gun whose barrel (2') is connected to a breech ring (16), and is seated to be displaced in a cradle barrel (3). To prevent a lifting effect of the barrel (2') inside the cradle barrel (3) upon firing, a slide-bushing bearing is disposed on at least the muzzle side of the barrel (2'). The bearing encompasses a barrel bushing (7'), in which the barrel (2') is disposed free from any lifting effect, and whose outside surface (8) slides in a form-fit (i.e., with the smallest possible amount of play) in the cradle barrel (3), so that the barrel (2') is independently guided to slide both axially and radially. The radial sliding guidance of the barrel (2') during firing is effected by tab-shaped protrusions (10'), which extend into corresponding, groove-shaped recesses (9') of the barrel bushing (7') and hold the barrel (2') in the center of the barrel bushing (7').

In an autoloading gun construction having the breach end of a barrel removably assembled to the forward end of a barrel extension which is positioned between and secured to wall sections of two opposing receiver plates of a receiver section, the improvement comprising an aperture formed thru each wall section, and a weld formed between edge portions of each aperture and adjacent portions of the barrel extension.

Existing floating handguards have the problem of adding size and weight to M16 style gas operated rifles because these tubular handguards attach to a relatively large diametral surface which lies outward of a firearm operating member or gas tube. Existing handguards are mounted thus so that the handguard inside surface will mechanically clear the gas tube. The present invention solves this problem by providing a handguard system integrated to a firearm, the system having a one-piece extended barrel nut with a smaller diameter outer surface configured to lie inward of the gas tube, between the gas tube and the barrel. A one-piece generally tubular handguard has an outer surface with a longitudinal rib and an inner surface with an inner diameter and a groove which is aligned with the rib. The handguard inner diameter engages the barrel nut outer surface and the groove provides clearance for the gas tube. The rib is configured to maintain the rigidity of the handguard adjacent the groove.

A barrel nut for coupling a barrel of a firearm to a receiver includes a body having a first end, an opposing second end, and an outer surface. A bore extends centrally through the body from the first end to the second end. A plurality of heat conducting fins extends radially outwardly from the outer surface of the body. A fastening element fastens the breach end of the barrel nut to the receiver.

The present invention is an improved quick change barrel system for a firearm. It features an interlocking trunnion and lock ring that hold the barrel in place proximate the receiver. Intermittent threading provides multiple points of interface. A foldable handle is provided to allow safe removal of the lock ring and additional torque for attachment and removal of the lock ring from the system.