The P38 concept was accepted by the German military in 1938 but production of prototype (“Test”) pistols did not begin until late 1939. Walther began manufacture at their plant in Zella-Mehlis and produced three series of “Test” pistols, designated by a “0” prefix to the serial number. The third series pistols satisfactorily solved the previous problems for the Heer and mass production began in mid-1940, using Walther’s military production identification code “480”. After a few thousand pistols the Heer changed all codes from numbers to letters and Walther was given the “ac” code.

Several experimental versions were later created in .45 ACP, and .38 Super, but these were never mass-produced. In addition to the 9×19mm Parabellum version, some 7.65×21mm Parabellum and some .22 Long Rifle versions were also manufactured and sold.