What weapon, designed by Aimo Lahti, was a descendant of the M-22 prototype and the KP/-26 production model?
Aimo Lahti:  Of the 50 weapons he designed, the best known is the Suomi M-31 SMG. Suomi KP/-31: The Suomi KP/-31 (Suomi-konepistooli or "Submachine-gun Finland", literally: "Machine-pistol Finland") was a submachine gun (SMG) of Finnish design used during World War II.
i don't know