AUTOMATIC RIFLE SEMI-FREE BREECHBLOCK Russian patent published in 2010 - IPC F41A3/50 

FIELD: small arms.

SUBSTANCE: semi-free breechblock mechanism can be incorporated with long-barrel small arms. Breechblock mechanism lever has its base hinged to breech frame. Said lever moves its head mechanically, with radial acceleration along bullet flight to make an angle to frame and pusher to unlock parts immediately after the shot to unlock the breechblock. The latter motion occurs due to relatively small weight of the lever and, lever forming arm and displacement of center of gravity towards lever head part when slide system stops at extreme front position. Powder gas pressure reduced in barrel bore and breechblock self-braking force decreased in breech frame thrust opening, breechblock opens to get forced into initial extreme rear position.

EFFECT: breechblock operation independent of gun blow-back.

4 cl, 5 dwg