High Quality Content by WIKIPEDIA articles! The `Suomi KP/-31` (Suomi-konepistooli or "Submachine-gun Finland") was a submachine gun (SMG) of Finnish design 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 Suomi KP.