Firearm with gas operated breech block unlocking means

Claim 1

A FIREARM COMPRISING IN COMBINATION: (A) MEANS FORMING: (1) A FRAME, (2) A GUN BARREL SUPPORTED BY THE FRAME, SAID GUN BARREL HAVING: (A) A MUZZLE END, (B) A BREECH END, (C) AN ORIFICE BETWEEN THE MUZZLE AND BREECH ENDS, (D) A BREECH BLOCK LOCKING ELEMENT AT THE BREECH; (B) MEANS FORMING A CHAMBER SURROUNDING THE GUN BARREL AND IN COMMUNICTION WITH THE ORIFICE IN THE BARREL, SAID SECOND MENTIONED MEANS INCLUDING: (1) A MOVABLE PART SLIDABLY CARRIED BY THE FIRST MENTIONED MEANS, SAID MOVABLE PART BEING MOVABLE REARWARDLY BY EXPANSION OF GAS IN SAID CHAMBER; (C) A BREECH BLOCK SLIDABLY AND TURNABLY CARRIED BY THE MOVABLE PART, SAID BREECH BLOCK HAVING: (1) A LOCKING ELEMENT, WHICH UPON TURNING OF THE BREECH BLOCK, COOPERATAES WITH THE FIRST MEMTIONED LOCKING ELEMENT FOR LOCKING THE BREECH BLOCK AGAINST THE BREECH; (D) MEANS ACTUATED BY SAID REARWARD MOVEMENT OF THE MOVABLE PART UPON EXPANSION OF THE GAS IN THE CHAMBER FOR FIRST TURNING THE BREECH BLOCK TO UNLOCK THE LOCKING ELEMENT ON THE BREECH BLOCK FROM THE LOCKING ELEMENT ON THE BARREL AND FOR THEREAFTER SHIFTING THE BREECH BLOCK REARWARDLY; (E) A SPRING NORMALLY URGING SAID MOVABLE PART FORWARDLY AND SUBSEQUENTLY TO THE SHIFTING OF THE BREECH BLOCK REARWARDLY, CO-OPERATING WITH THE LAST MENTIONED MEANS FOR SHIFTING THE BREECH BLOCK FORWARDLY AND FOR THEREAFTER TURNING THE BREECH BLOCK TO LOCK THE LOCKING ELEMENT ON THE BREECH BLOCK WITH THE LOCKING ELEMENT ON THE BARREL; (F) AND A SHOULDER ON THE BARREL FOR LIMITING FORWARD MOVEMENT OF SAID MOVABLE PART BY THE SPRING.