Suomi KP/-31

Suomi KP/-31
Suomi KP/-31
TypeSubmachine gun
Place of originFinland
Service history
In service1931–1980s
Used bySee Users
Wars
Production history
DesignerAimo Lahti
Designedlate 1920s
ManufacturerTikkakoski
Produced1931–1953
No. builtApprox. 80,000
Variants
  • Kpist m/37
  • Kpist m/37-39
  • Kpist m/37-39F
  • Lettet-Forsøgs
  • Madsen-Suomi
  • Hispano Suiza MP43/44
Specifications
Mass4.6 kg (10.14 lb)
Length
  • 870 mm (34.3 in)
  • 925 mm (36.4 in) (SJR)
  • 740 mm (29.1 in) (bunker version)
Barrel length314 mm (12.4 in)
Cartridge9×19mm Parabellum, 7.65mm Parabellum[4]
ActionStraight Blowback
Rate of fire750–900 rounds/min
Muzzle velocity396 m/s (1,299 ft/s)[5]
Effective firing range200 m[6]
Feed system20-, 36- or 50-round box, 40- or 71-round drum. Also modified German MP 38 & MP 40 32-round box magazine
SightsFront blade, rear notch

The Suomi KP/-31 (Finnish: Suomi-konepistooli m/31 or "Finland-machine-pistol mod. 1931") is a Finnish submachine gun that was mainly used during World War II. It is a descendant of the M-22 prototype and the KP/-26 production model, which was revealed to the public in 1925. It entered service in Finland in 1931, and remained in use until the 1980s.[3]

The Suomi KP/-31 is regarded by many[7] as one of the most successful submachine guns of World War II. It also had a profound effect on the conflict beyond Finland as the Soviet authorities, who had been dismissive of submachine guns, were persuaded of their fatal efficiency by the Finnish forces in the Winter War of 1939–1940.[8] Though a relatively early design, the Suomi was a formidable weapon: highly controllable[9] and with accuracy similar to that of the mass-produced PPSh-41[10] but at the cost of a significantly higher mass to absorb recoil, with a lower rate of fire and an equally large magazine capacity.[10] Its major disadvantages were its higher weight, high maintenance requirements and high production cost, which led to the later introduction of the KP/-44, a close copy of the Soviet PPS-43 but accepting the existing magazines and drums for the KP/-31.

The M-22 and KP/-26 were made by Konepistooli Oy, founded by Master Armorer Aimo Lahti, Captain V. Korpela, Lieutenant Y. Koskinen and Lieutenant L. Boyer-Spoof. The Suomi KP/-31 was designed by Koskinen and Lahti.

  1. ^ a b Thompson 2017, p. 6.
  2. ^ Thompson 2017, p. 4.
  3. ^ a b Thompson 2017, p. 5.
  4. ^ "La Guerra del Chaco: fighting in El Infierno Verde: Part II: tanks, airplanes, submachine guns". Archived from the original on 2022-11-23. Retrieved 2022-11-24.
  5. ^ "Gunwritersin Suomi-KP, osa 5". Guns.connect.fi. Archived from the original on 2017-02-07. Retrieved 2011-12-06.
  6. ^ "Suomi submachine gun (Finland)". Modern Firearms. 27 October 2010. Archived from the original on 19 September 2017. Retrieved 12 February 2017.
  7. ^ Combat Guns: An Illustrated Encyclopedia of 20th Century Firearms, Osprey, 1987 ISBN 9780600551782.
  8. ^ Soviet Submachine Guns of World War II. Chris McNab, Osprey Publishing, p. 9.
  9. ^ "Suomi m/31 - Finland's Excellent Submachine Gun" Archived 2023-01-06 at the Wayback Machine. Forgotten Weapons.
  10. ^ a b Kekkonen, P. "Suomi Submachine Gun, KP/-31, part 2/2". Gunwriters. Archived from the original on 2 February 2017. Retrieved 12 February 2017.