The design-work began around 1965, with the first series (known as "pre-73" or just
P9 without S) being produced between 1969 and 1973. 485 single-action P9s were produced before being discontinued. A traditional double action version, the
P9S (the
S standing for
Spannabzug, or "double-action trigger") was manufactured in greater numbers, from 1973 all the way up to 1978, until being discontinued again. .45 ACP variant was introduced in 1977. The P9S was adopted by the
US Navy for use with a
sound suppressor. The suppressors of the period were comparatively large and the model frequently used with the P9S makes the pistol's sights unusable, so the suppressor was equipped with sights instead. The fixed barrel of the P9S allows the pistol to operate reliably with the suppressor attached without requiring the
recoil booster most recoil-operated pistols need to accommodate the extra mass a suppressor adds to the weapon's muzzle. A shortened version, the
P9K (the
K standing for
Kurz, or "short") was made in prototype form. Until Theodor Koch's death in October 1976, four prototypes of a shortened version of the P9K were also produced, but was never put into production. In addition to the standard P9S, a
P9S Target model was also offered. This model included a taller front sight, a windage and elevation adjustable rear sight, an adjustable trigger over-travel stop, and an adjustable trigger that could be adjusted down to as low as approximately a 2.5# pull. The P9S Target model was offered in both 9mm as well as .45 ACP. ==Users==