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.
.38 S&amp;W The .38 S&W (9×20mmR) is a revolver cartridge developed by Smith & Wesson in 1877 for use in the S&W .38 Single Action. Though similar in name, it is not interchangeable with the later .38 Smith & Wesson Special due to a different case shape and slightly larger bullet diameter.