The Russian PM pistol resulted from a design competition for replacing the Tokarev TT-33 semi-automatic pistol and the Nagant M1895 revolver. Rather than building a pistol to an existing cartridge in the Soviet inventory, Nikolai took up the German wartime Walther Ultra design, fundamentally an enlarged Walther PP, utilizing the 918mm cartridge designed by B.V. Semin in 1946. For simplicity and economy, the Russian PM pistol was of straight blowback operation, with the 918mm cartridge being the most powerful cartridge it could safely fire.<br><br>