Suomi KP/-31

The Suomi KP/-31 is a Finnish submachine gun designed by Aimo Lahti and manufactured by Tikkakoski Oy, entering service in 1931 and remaining in use into the 1980s. Chambered in 9x19mm Parabellum, and in some versions 7.65mm Parabellum, it proved one of the most successful submachine guns of the Second World War, and its performance against Soviet forces in the Winter War helped convince Soviet commanders, who had previously doubted the weapon class, of the submachine gun's battlefield value. It offered highly controllable automatic fire and accuracy comparable to the later Soviet PPSh-41, though it was heavier and slower-firing with an equivalent magazine capacity.