The Makarov pistol resulted from a design competition for replacing the Tokarev T-33 semi-automatic pistol and the Mosin Nagant revolver.Rather than building a pistol to an existing cartridge in the Soviet inventory, Nikolai Makarov utilized essentially the "9mm Ultra" cartridge which had been designed by Carl Walther G.m.b.H. for the German Luftwaffe during the Second World War. Walther's cartridge became the 9x18mm Makarov. For simplicity and economy, the Makarov pistol was of straight blowback operation, with the 9x18mm cartridge being the most powerful cartridge it could safely fire. Although the nominal calibre was 9.0mm, the actual bullet was 9.22mm in diameter, being shorter and wider and thus incompatible with pistols chambered for 9x19mm Parabellum cartridges. Consequently, Soviet ammunition was unusable in NATO firearms, and in the event of war NATO forces would be unable to use ammunition from Soviet sources.