The Suomi Model 1931 was a Finnish 9mm submachine gun used by German and Finnish troops during World War II. Developed by Suomi, it entered service in 1931 and first saw combat action during the Spanish Civil War, and then during the 1940 Russian invasion of Finland. The Suomi M31 was one of the most well-manufactured submachine guns ever made, for practically every part was machined from solid metal. It had a straight blow-back action and was fitted with a long barrel which was accurate enough for aimed fire at most combat ranges. The feed system of the Suomi M31 could used different magazines: a 30-round and a 50-round vertical box magazines, and a 71-round drum magazine.
There were several export models of the Suomi M1931, some of them with small bipods under the barrel or body, which were acquired by Sweden and Switzerland, who both set up their own production lines. This Finnish submachine gun was also adopted by the Polish police before 1939, and examples popped up during the Spanish Civil War on both sides. On the Eastern Front of World War II, it was used by some Waffen-SS units. German Waffen-SS infantry units preferred to use the Suomi M1931 as it was very accurate at ranges up to 300 m (330 yards); thus it could be used not only in urban warfare, but also in open battlefields.
Type: submachine gun
Country of origin: Finland
Caliber: 9 mm
Cartridge: 9x19mm Parabellum
Barrel length: 314 mm ( 12.36 in)
Rate of fire: 900 rpm
Effective range: 300 m
Maximum range: 500 m
Magazines: 30/50-round box magazines; 71-round drum magazine
Weight (loaded): 7.04 kg (15.52 lb)