Abstract: A double-action trigger mechanism for firearms having a pivoted trigger and hammer with a draw-bar connecting them for cocking the hammer by means of the trigger, together with a trigger-blocking magazine safety for preventing firing of the gun when the cartridge magazine is removed. A multiple purpose spring is provided which acts as a trigger-return spring, a magazine-safety spring and a draw-bar spring. In addition, provision is made for limiting the retraction of the breech-bolt or slide when the magazine is removed so that a live cartridge in the chamber can not be extracted or a fresh cartridge can not be inserted into an empty chamber until the magazine is replaced.