Abstract: A passive safety mechanism is shown installed in a semi-automatic pistol. The passive safety mechanism includes a cylindrical body rotatably mounted within the slide assembly which may be rotated between an engaged position and a disengaged position using a key inserted into a keyway in the exposed axial end of the cylindrical body. In the engaged position, a portion of the body blocks the hammer assembly from contacting the firing pin, and a circumferential surface depresses the ejector and magazine depressor lever and firing pin safety lever. Rotation of the cylindrical body within the slide assembly is prevented or resisted through friction and spring tension created by a spring-biased pin carried in a transverse bore in the cylindrical body and riding within a channel in the slide assembly.

Abstract: A firearm locking mechanism comprising block or body having a conventional pin-tumbler or cylindrical lock mounted generally vertically therein. The block or body is received within the exposed area between the breech and open breech block in a firearm directly above the magazine, with an engagement member connected to the bottom of the lock being received within the top of the magazine and rotated by the lock. The engagement member engages beneath and between the cartridge-retaining surfaces at the top of the magazine to secure the lock and body to the top of the magazine, thereby preventing the breech block from closing or the magazine from being removed. The locking mechanism similarly prevents moving the firing pin assembly into proximity with any cartridge remaining in the barrel or magazine.