| 摘要 |
<p>A firearm comprises a barrel (14) having a bore (36) and a receiver (12) forming an ignition chamber (18). A bolt (20) is slidable in the ignition chamber (18) and includes a striker projection for igniting a primer of a projectile (26). A bolt advancing mechanism comprises arms (42) whose forward ends are rotatably mounted on the bolt such that the rearward ends of the arms (42) are movable laterally relative to the barrel axis. A boss (50) is carried at the rear end of each arm. An actuator member (54) is movable in the fore-aft direction and includes inclined slots (52) on which the bosses (50) slide. Each boss (50) is movable laterally by its slot in response to the boss (50) becoming aligned with a lateral groove (82) in the receiver, this lateral movement being In a direction tending to displace the bolt forwardly. The actuator member (54) pushes the bosses (50) and the bolt (20) forwardly to shift the projectile (26) to a firing position, cam the bosses (50) into the grooves (82) to displace the bolt (20) further forwardly and ignite the primer, and blocks movement of the bosses (50) from the grooves (82) until ignition occurs, whereupon the actuating member (54) is pushed rearwardly and the bosses (50) are displaced outwardly.</p> |
