Abstract: A firearm is disclosed comprising a frame, a firing mechanism mounted on the frame, and a barrel mounted on the frame having a longitudinal axis aligned with the firing mechanism. A drum magazine is mounted for rotation about a central axis on the frame, the magazine having a plurality of circumferentially spaced cartridge chambers, each chamber being positioned so that when rotated into an appropriate position it registers with the firing mechanism and the barrel. A shroud is circumferentially mounted over the barrel and is rotatable with respect thereto. An indexing means is operable by means of a to-and-fro relative rotation between the shroud and the frame, to rotate the drum magazine from a fire position which a said cartridge chamber registers with the firing mechanism to a next succeeding fire position in which a next succeeding cartridge chamber registers with the firing mechanism.