Abstract: A machine pistol for cartridges of different types comprises a barrel, a cartridge chamber within said barrel for housing a cartridge in a firing position, and a magazine for feeding cartridges to the cartridge chamber. A percussion pin is provided for firing the cartridge. A breech block is movable relative to the barrel for actuation of the percussion pin. A longitudinal portion of the breech block has a small radial clearance relative to a wall of the barrel and defines a semicylindrical chamber surrounding the barrel over a certain longitudinal length. The percussion pin is positioned in the wall of the barrel and is radially movable relative to the barrel under the action of a portion of an actuator device movable with the breech block.