The block (B) is hollowed along its upper surface (I) to assist in inserting a cartridge into the firing chamber (J). To fire the cartridge the block is raised to position the firing mechanism (K) against the cartridge. The firing mechanism consists of a helical spring around a pointed metal striker, the tip of which passes through a hole in the face of the block to impact the percussion-cap of the inserted cartridge. As the lever (E) is moved forward the tumbler (G) revolves and one of its arms engages and draws back the spring until the tumbler is firmly locked in the notch (H) and the spring is held by the rest-piece (L) which is pushed into a bend in the lower part of the tumbler.