PM-63 having the official designation as "9mm Submachine Gun Model 63" (9mm pistolet maszynowy wz.63), also known as RAK is a Polish submachine gun designed by a team consisting of Piotr Wilniewczyc, Marian Wakalski, Grzegorz Czubak, and Tadeusz Bednarski. Popular acronym "RAK" meaning "cancer", but also "crayfish" in Polish language supposed to come from a phrase "Ręczny Automat Komandosów", translating in English as "Handheld Commando Automatic Weapon". According with opinion of Stanisław Kochański however, who is the author of many books and articles about small arms, such origin of that acronym is simply not true. PM-63 was designed for crews of armored vehicles, platoon commanders as a side weapon, and for paratroopers. This gun belongs to the same class of weapons as Soviet APS machine pistol and Tschechoslovakian Sa vz.61 "Skorpion" submachine gun. PM-63 design is also similar to Bechowiec-1 submachine gun designed by Henryk Strąpoć and prototype MCEM-2 (Machine Carbine Experimental 2) designed by Jerzy Podsędowski in Great Britain. RAK does not have receiver, but instead has a handgun-like steel frame and the steel slide completly enclosing the barrel in a manner utilized in semiautomatic pistols and Bechowiec-1. PM-63 has magazine in pistol grip similar to MCEM-2. Prototype of RAK had a wooden foreguard and steel folding stock. In prototype versions of the gun the stock buttplate in collapsed position could be used as a front grip. PM-63 was adopted for service in Polish Armed Forces in 1965. One of its designers- Piotr Wilniewczyc- died in 1960.
Konstrukcja PM-63
PM-63 is a blowback operated weapon which fires from an open bolt. It is quite unique design having handgun-like steel frame, and firing in "open bolt" configuration. RAK is equipped with a slide catch holding the slide in its rear position after emptying the magazine. Insertion of new loaded magazine into the well allows shooter to fire without first releasing the slide catch. Front of the slide protrudes beyond the muzzle and acts as recoil compensator, and also could be used to recock the weapon with one hand by pressing the front end of the weapon against a hard surface. The fire rate reducer is mounted in the rear of the slide. First versions of PM-63 had one-part fire rate reducer made from tungsten, but later versions of RAK had the modified two-part fire rate reducer made out of steel. Extractor is mounted on the left side of the frame with a front portion of the magazine acting as ejector. Gun has field-strip removable barrel rifled with 4 groove right hand twist. Recoil spring on the spring guide is located under the barrel. On the left side of the receiver, just behind the pistol grip, there is a safety lever having "fire" in front position and "safe" in its rear position. Safety is also immobilizing the slide. Shooter can engage safety lever either with slide in its front or rear position. PM-63 has a double stage trigger mechanism for single and full auto fire. (Similar to Steyr's AUG). Firing pin is fixed and mounted on the slide's bolt head. RAK is chambered for Soviet 9x18mm 57-N-181S cartridge better known as 9x18mm Makarov. The gun is fed from double column, single feed magazines having capacity either 25 or 15 rounds. Magazine well is located in the pistol grip. Magazine latch is located under the pistol grip and locks against a bottom of the magazine. Flat plastic panels are mounted on both sides of the pistol grip. PM-63 has folding plastic front grip and a steel retractable stock. Rear of the stock is terminated with small rotating buttplate. The sling attachement eye is placed under the rear portion of the frame. Gun is equipped with iron sights. Rear sight of the flip type is graduated for 75 or 150 meters only.
PM-63 with magazine for 25 catridges
PM-63 with slide in front position (courtesy: jac-t from forum)
PM-63 with slide in front position and unfolded front grip (courtesy: jac-t)
PM-63 with slide in rear position, unfolded front grip and stock in retracted position (courtesy: jac-t)
PM-63 and PM-98 (courtesy: jac-t)
PM-63 25 and 15 naboi rounds magazine
PM-63 in Rambo III (courtesy: Herrmannek from forum)
Field stripped PM-63. Graphics from a book "Polish Peoples Army Small Arms and Ammunition" (Broń i Amunicja Strzelecka LWP), author: Stanisław Torecki
PM-63 Accesories
PM-63 Holster
PM-63 was issued with a set of 4 magazines. Two of three having capacity of 25 rounds, and the fourth one holding 15 cartridges. The special blank firing barrel could be mounted in lieu of regular one, but it would not allow to fire regular ammunition. There was a magazine loader designed for PM-63, but that device was never accepted for service in Polish Armed Forces.
Other PM-63 version
The was a version of PM-63 chambered for 9x19mm Parabellum cartridge. This version sports strenghtened and heavier slide. RAK in 9mm Para. had never entered mass production.

The was a prototype version of silenced PM-63. It was chambered for standard Soviet 9x18mm 57-N-181S cartridge.

Type 82 is a Chinese copy of PM-63 manufactured by NORINCO. Polish submaschine gun probably drew interest of Chinese designers after Chino-Vietnamese war, during which crews of Vietnamese tanks used PM-63. Type 82 exists in versions with original iron sights, and also with modified sights. Type 82 was never officially adopted in service by Chinese Army and had never been produced in large quantities. (Chinese Army adopted Type 79 submachine gun instead). PM-63 was probably the only Polish weapon which was copied by the foreign country.
Type 82 submachine gun
PM-63 summary
PM-63 is probably the first Polish mass produced submachine gun, however according to some, the "Błyskawica" had been the first Polish submaschine gun manufactured in large quantities. PM-63 was one of the first small submachine guns designed specifically for crews of armored vehicles. RAK was designed to fire relatively weak cartridge, but it was light and did not have the heavy recoil. Some soldiers didn't like PM-63 for its lack of receiver and for double stage trigger, but in opinion of others those were not bad features. Today, PM-63 could be compared with FN P90 and MP7 submachine guns. RAK was replaced in the 90-ties as a standard service weapon by PM-84P chambered for 9x19mm Parabellum Cartridge due to adoption and integration of weapons systems used by Polish Armed Forces with NATO standards. .
9x18mm 57-N-181S
muzzle velocity
muzzle energy
barrel lenght
sight line lenght
333mm with stock in non retracted

583mm with stock in retracted
145mm with magazine for 15 catridge

213mm with magazine for 25
1.6kg without magazine

1.85kg with full load magazine for 15

2.1kg zwith full load magazine for 25
double column single feed for 15 and
25 cartridges
fire mode
single shot and full auto
rate of fire
650 rpm
PM-63 with stock in retracted position and unfolded front grip