The forward movement of the unbolting ramps with the mass body causes the slide to be unbolted. A tube (1) is fixed to a frame (2) and the slide (3) is connected to the tube via a transmission catch (4). The transmission catch is supported on the unbolting ramps (5) in the rearmost position and the breech block is catch. In the foremost position of the transmission component the breech block is open. The unbolting ramp forms a unit with the mass body (6) which is movable in the tube direction. The mass body is pressed by a spring (7) in the direction of the magazine.
