Suomi KP/-31

Finnish soldier armed with a Suomi KP

Finnish soldier armed with a Suomi KP

The KP/-31 Suomi (Suomi-konepistooli or “Submachine gun Finland”) was a submachine Finn, who saw service during World War II. The design came from the M-22 prototype and model KP/-26, which appeared in 1925. The Suomi-Konepistooli KP/-31 (automatic pistol Finland) often abbreviated as Suomi KP.


The Suomi KP/-31 is considered by many as one of the most successful submachine guns of World War II, in addition to developing the drum of 71 balls which was later copied and adopted by the Soviet Union for his PPD submachine- 40 and PPSh-41. Its accuracy when compared with the PPSh-41 was higher standard, due in part to its longer barrel, with the same rate of fire and large magazine capacity. The main disadvantage of the Suomi KP/-31 was its high production cost.

The addition KP/-31 Suomi new features incorporated, including recoil spring assembly within the bolt so that the submachine is shorter. Its magazine of 50 bullets straight into four columns was more reliable than the first drum of 50 rounds, using this design in Argentine submachine charger Hafdasa C-4 and 60 bullets today chargers compatible with the AK-74.


THE M-22 and KP-26 were manufactured by Konepistooli Oy, founded by Finnish arms designer Aimo Lahti, Captain V. Korpela, Y. and Lieutenants Koskinen and L. Boyer-Spoof. The Suomi KP-31 was designed by Koskinen andLahti.

Tikkakoski Oy began to mass produce KP/-31 Suomi in 1931, most of these weapons being bought by the Finnish Armed Forces. Finnish armed forces were equipped with about 4,000 submachine guns KP-31 when he started the Winter War. During the war, the design was modified with the addition of a muzzle brake, which increased by 55 mmto the length of the SMG. The modified version was called KP/-31 SJR (suujarru, muzzle brake in Finnish). Aimo Lahti did not agree with this amendment because he thought it would reduce the reliability of the weapon. Finally, only half of the service were KP/-31 in SJR version. At baseline, KP/-31 was provided as a substitute and submachine gun proved inadequate for this role. Instead, the soldiers learned through trial and error how to use submachine effectively. At the time of the Continuation War, Finnish military doctrine was modified to include both a KP-31 and a light machine gun (usually a captured Degtyarov DP) in every infantry platoon, being increased to two per pack by 1943 KP/-31 . The KP/-31 production continued to increase with the intent of a third submachine agergar each platoon, but this plan was shelved in 1944 when he finished the Continuation War

Also in 1941 there was a special version for bunker in limited quantities (a total of 500 submachine built) with a thin shirt cannon to shoot through the narrow slits of defensive bunkers. This version had no head and was equipped with a pistol. An even more limited version was produced for use as secondary armament in the pockets of the Vickers 6-ton tanks, but only a dozen were built before the cessation of production due to the start of the Winter War. Production never resumed, as captured DP Degtyaryov ametralladoas proved far superior in this paper. Like the bunker version, the version for tank only had a pistol and had no butt, and the tank could be removed quickly and be equipped with a standard barrel jacket to be used as infantry weapon if necessary. The tank version was in the Finnish Army inventory until the late 1980s, even though the tank was designed which was withdrawn in 1959, possibly because the Army had forgotten its existence.

The Suomi KP/-31 was also manufactured under license in Sweden by Husqwarna, Madsen in Denmark and Switzerland, where he was known as Hispano-Suiza MP43/44.

In 2009 there was a semi-automatic version of the Suomi KP/-31 for the civilian market in theUnited States, replacing the receiver and lengthening the barrel to meet the requirements of the National Act on Firearms.


  • 3042 bought from Finlandduring World War II, and probably supplied the Wehrmacht and the Waffen-SS. They were also supplied to Armeeoberkommando submachine Norwegen120 in 1942 for use in the Finnish front. Most of these submachine leftFinland for the withdrawal of German troops in 1944 and were used on other fronts.
  • 5505 purchased between 1940-1942.
  • 1250 purchased between 1942-43.
  • Madsen and Hovea built at least 1,400 copies of M/31 M/41 calls, derived from submachine-Forsøgs Lettet.
  • 485 purchased in 1937
  • The Norwegian soldiers stationed inSwedenduring World War II used the Swedish variant m/37-39. They were used by the Norwegian armed forces until the 1980s, primarily for the Navy and the National Guard.
  • used by the Policja (Police) Polish.
  • Husqvarna AB Vapenfabriks licensed manufactured 35,000 units before and during World War II, some of which were imported fromFinland. Kpist called M/37 (9mm cartridge used Browning Long) for its year of adoption, in 1939 Sweden decided to adopt the 9 x 19 Parabellum and new m/37-39 kpist SMGs are called.
  • used submachine guns captured.
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