The PM-63 RAK (often incorrectly referred to as Ręczny Automat Komandosów—"commandos' hand-held automatic"; the name itself means cancer or crayfish in Polish) is a Polish 9×18mm submachine gun, designed by Piotr Wilniewczyc in cooperation with Tadeusz Bednarski, Grzegorz Czubak and Marian Wakalski. The RAK combines the characteristics of a self-loading pistol and a fully automatic submachine gun. History Development of the RAK dates back to the late 1950s when the concept was first proposed at the Warsaw University of Technology in response to a requirement for a light hand-held defensive weapon for rear-echelon soldiers such as gun crews and vehicle drivers. After the death of the chief designer Piotr Wilniewczyc in 1960, the submachine gun’s development was eventually resumed and completed by the state-operated Łucznik Arms Factory in the city of Radom, where it was produced until 1977. After close examination, the PM-63 was accepted into service with the People's Army of Poland and police in 1965 as the 9 mm pistolet maszynowy wz. 1963 ("9 mm submachine gun model 1963"). Small numbers of the weapon were exported to several Arab countries, Vietnam and the former East Germany. A slightly modified, unlicensed version of the PM-63 was produced by the People’s Republic of China as the Type 82, who sold the weapon to politically allied nations in Asia. Design details Operating mechanism The RAK is a selective-fire straight blowback–operated machine pistol, fired from the open bolt position. Unlike most submachine guns firing from an open bolt, the PM-63 has a reciprocating external breech bolt, also known as a slide. The slide is part of the fire rate-reducing device. When the trigger is pulled the slide is released and driven forward by the return spring, stripping a round from the magazine and feeding it into the chamber. As soon as the cartridge is lined up with the chamber the extractor grips the rim and the gun fires while the slide is still moving forward. The firing impulse retards the forward movement of the slide and drives it back. The extractor grips the empty case until the ejector pushes it through the ejection port in the right of the slide. The slide continues to the rear and the return spring, located under the barrel, is fully compressed. The slide rides over a retarder lever which snaps up and holds the slide to the rear. The rate-reducing device, an inertia buffer in the