The P38 concept was accepted by the German military in 1938 but production of actual prototype ("Test") pistols did not start 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 satisfied
the previous problems and production for the Heer (German Army) 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. All production was performed at the Walther plant
until mid- to late 1942 when additional production began at the Mauser plant in Oberndorf (code "byf" until early 1945, then "svw") and at the Spreewerk plant
in Hradek and Nisou, Czechoslovakia ("cyq"). Production continued until the end of the war and into the post war period. The early Walthers, until late 1941,
were made to almost commercial standards of fit and polish. As the pressures of war required increased production the exterior finish declined but the
operating components of the P38 remained remarkably well-made throughout the war, especially at Mauser.

Three firms made components for P38 production:

Fabrique Nationale-- slides, frames and locking blocks (M or M1)
Ceska Zbrojovka, CZ (Böhmische Waffenfabrik)-- barrels (fnh)
Erste Nordböhmische Metallwarenfabrik -- magazines (jvd)

The French manufactured P38 pistols from captured parts at the Mauser factory from May or June of 1945 until 1946. These are identifiable by the presence
of a five-pointed star stamped on the slide. Total German production is estimated at more than 1,200,000 pistols. Production of the P38 resumed at a new
Walther factory in Ulm, West Germany under the name Pistole 1 (P1) in 1958 for West German Police and the Bundeswehr. It remained in Walther
production, in several revised iterations, until the early 1990s.

The P38 was the first locked-breech pistol to use a double-action trigger. The shooter could load a round into the chamber, use the de-cocking lever to safely
lower the hammer without firing the round, and carry the weapon loaded with the hammer down. A pull of the trigger, with the hammer down, fired the first
shot and the operation of the pistol ejected the fired round and reloaded a fresh round into the chamber, all features found in many modern day handguns.

The first designs submitted to the German Army featured a locked breech and a hidden hammer, but the German Army requested that it be redesigned with
an external hammer. This led to the subsequent adoption of the P38 in 1940. Several experimental versions were later created in .45 ACP, and .38 Super, but
these were never mass-produced. In addition to the 9 mm Parabellum version, some 7.65x22mm Parabellum and some .22 Long Rifle versions were also
created and sold.

The barrel-locking mechanism operates by use of a wedge-shaped locking block underneath the breech. When fired both the barrel and slide recoil for a
short distance, where the locking block drives down, disengaging the sliding and arresting the movement of the barrel.

The P38 uses a double action trigger design similar to the earlier Walther PPKs, and a loaded chamber indicator was also incorporated.