Gas operated firearm

Abstract

A known gas operated firearm has been modified to be of more compact size and reduced weight while retaining the firepower, the features, and most of the components of its predecessor. A bolt assembly reciprocably mounted in a longitudinal cavity of a receiver assembly for movement between recoil and battery positions has a forwardly facing pressure surface and first and second longitudinally extending coaxial bores. The annular flange of a firing pin is slidable in the second bore and the bolt assembly includes a transversely extending retaining pin engageable by the annular flange to define an aftward terminal position of the firing pin. A recoil assembly includes a pair of tungsten weights mounted in the longitudinal cavity for rectilinear movement with the bolt assembly between the recoil and battery positions and includes means to bias the bolt assembly toward the battery position. A trigger mechanism includes a hammer biased for movement toward the firing position from a cocked position whose recessed face squarely impacts the firing pin. A second transversely extending recess in the hammer face provides clearance for the transversely extended retaining pin. Expanding gases from a cartridge whose bullet has passed a gas port proceeds past the gas port, then through a gas passage tube and against the pressure surface of the bolt assembly for driving the bolt assembly toward the recoil position. The tungsten weights are of a magnitude coordinated with the velocity of the recoil assembly so as to reduce rebound in the battery position of assembly during automatic fire.