What cartridge, also known as 9 mm Luger by the C.I.P. or 9 mm NATO by NATO, is used in the submachine gun the MP 40?
MP 40 The MP 40 ("Maschinenpistole 40") was a submachine gun chambered for the 9×19mm Parabellum cartridge. It was developed in Nazi Germany and used extensively by the Axis powers during the Second World War.
M1941 Johnson machine gun The M1941 Johnson Light Machine Gun, also known as the "Johnson" and the "Johnny gun", was an American recoil-operated light machine gun designed in the late 1930s by Melvin Johnson. It shared the same operating principle and many parts with the M1941 Johnson rifle and the M1947 Johnson auto carbine.