Firearm Infobox
Name, Image, type, origin
Name Suomi KP-31
Image 300px
Suomi KP-31
Type Service submachine gun
Place of origin Flag of Finland Finland
Service history
In service 1931–1982
Used by Finland, Sweden, Denmark and Switzerland among others
Wars the Winter War and WWII (or the Continuation War)
Production history
Designer Aimo Lahti
Designed first prototype in 1920 or 1921
Manufacturer {{{manufacturer}}}
Produced 1931–1944
Number ~80000
Variants Kpist m/37 (Swedish cal. 9x20 mm Browning Long)
Kpist m/37-39 (Swedish with shortened barrel, cal. 9x19mm Parabellum)
Kpist m/37-39F (Finnish model, cal. 9 x 19 mm Parabellum)
Madsen-Suomi (Danish model, cal. 9x19mm Parabellum)
Hispano Suiza MP43/44 (Swiss model, cal. 9x19mm Parabellum) among others
Weight 4.6 kg
Length 870 mm
Width {{{width}}}
Height {{{height}}}
Barrel length 314 mm
Diameter {{{diameter}}}
Crew {{{crew}}}
Cartridge 9x19mm Parabellum
Caliber {{{caliber}}}
Action blowback
Muzzle velocity 396 m/s
Effective range ~200 m
Maximum range {{{max_range}}}
Other identifying characteristics
Wood parts (Y/N) {{{wood}}}
Common color {{{color}}}
Imprint {{{imprint}}}

The Suomi-konepistooli KP-31 (Submachine Gun Finland KP-31) was a submachine gun of Finnish manufacture that was in service during World War II. It was a descendant of the M-22 prototype and the KP-26 production model, which was revealed to the public in 1925. The Suomi-konepistooli KP-31 is often abbreviated to just Suomi KP.

The Suomi KP-31 is regarded by many as one of the best submachine guns of World War II and it was so successful that some features from the Suomi KP-31 were copied in the design of the Soviet PPSh-41 submachine gun, such as the magazine.[1] The accuracy compared to the mass-produced PPSh-41 is superior, thanks in part to a noticeably longer barrel, with the same rate of fire and an equally large 71 round drum magazine. If anything, it also possesses superior durability over the similar Russian SMG.

The M-22 and KP-26 were made by Konepistooli Oy (literally "Submachine gun company" in Finnish), founded by Master Armorer Aimo Johannes Lahti, Captain V. Korpela, Lieutenant Y. Koskinen and Lieutenant L. Boyer-Spoof. The Suomi-submachine gun KP-31 was designed by the duo of Lieutenant Koskinen and Master Armorer Lahti.

The Suomi KP-31 went into serial production in 1931 by "Tikkakoski Oy" and most of these weapons were bought by the Finnish Defence Forces. The Finnish Defence Forces were equipped with about four thousand Suomi KP-31 submachine guns when the Winter War started.

A variant with an underslung Flamethrower was produced but not much is known about this.

Suomi was also manufactured under license in Sweden, Denmark, and Switzerland. Tank and pillbox variants were also developed and produced in Finland.

See alsoEdit

External linksEdit


  1. Mosier, The Blitzkrieg Myth, p.86.


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