Ruger Mark IV pistols are the latest evolution of Ruger's original 1949 Standard Auto Pistol. Ruger Mark IV improvements include the use of a solid one-piece fully machined grip frame, a simple take-down mechanism for easy disassembly and cleaning, an improved bolt stop leaver, an ambidextrous manual safety, and a drop-free magazine release. The Ruger Mark IV 22/45 Tactical has a lightweight polymer grip frame with rubberized replaceable grip panels that simulate the classic feel and grip angle of the 1911. The barrel is threaded for the addition of muzzle accessories, and Picatinny rails are factory-installed on this model. The Ruger Mark IV 22/45 uses Mark IV 22/45 magazines only. Mark IV 22/45 magazines are not compatible with the Mark III 22/45. The Ruger Mark IV pistol is equipped with a magazine disconnect. This device prevents the trigger from being pulled if the magazine is removed from the pistol.