Makarov: The Soviets Adopt Some Weird Proprietary Caliber
The Makarov, designed by Nikolay Makarov, was the Soviet Union's new post-WW2 handgun. The whole Soviet small arms suite was changed in the late 1940s and early 1950s, and the Makarov was intended to address a number of concerns with the TT33 Tokarev pistols. The Tokarev was a relatively challenging pistol to shoot, with its potent 7.62x25mm cartridge. It was also associated with a lot of accidental discharges, as it had no mnaul safety besides a half-cock notch in the hammer. The new pistol needed to be small, lighter, easier to use, and safer. In addition, with the replacement of the PPSh and PPS submachine guns with the new Kalashnikov, the pistol no longer needed to share ammunition with any other small arms. This led to development of a moderately-powered 9mm cartridge, the 9x18 Makarov (actually designed by Boris Semin). That cartridge used a 9mm land diameter, meaning that it was actually 9.2mm by typical Western measurement (groove diameter).
Mechanically, the Makarov drew many design elements from the Walther PP family. It was a simple blowback pistol with a single stack 8-round magazine and a double action hammer fired system. It was formally adopted in 1951, with full scale production beginning at Factory 622 in Izhevsk in 1953 and the final perfected design realized in 1955. It remained the standard Soviet military sidearm right up to the collapse of the Soviet Union.
In addition to Soviet production, the Makarov was manufactured in East Germany, Bulgaria, and China. A greta many of these have been imported into the US, although not very many Soviet examples.