Abstract: A multipurpose safety lock for firearms with automatic, semi-automatic or manually operated means of ejecting cartridge cases after firing is inserted in the ejection port when it is in the open position; and for firearms with a revolving cartridge-receiving cylinder, is inserted in the frame made vacant when the cylinder is in an open position. The lock comprises a body with a cylindrical assembly at the end inserted in the ejection port or the open frame, with a lock bolt extendible into the breech and barrel and lockable in that position by turning a key. While the lock bolt is in the locked condition in the breech and barrel the firearm cannot be put into firing condition and cannot be discharged.