Heckler & Koch engineers of West Germany began design of a new, all-modern compact semi-automatic pistol in 1965. The result of this work became the popular P9 series which appeared in 1969 and saw a production run lasting until the late 1970s. The P9 made use of modern construction methods of the period that included polymers for weight reduction and stamped steel for high-tolerance components such as the slide.
The P9 was typically adopted in 9x19mm Parabellum pistol cartridge but other market forms emerged to support the 7.65x22mm Parabellum as well as the popular .45 ACP round. The action was based on the HK tried-and-true roller-delayed blowback arrangement though slightly modified in this sidearm. The barrel was also completed with polygonal rifling. The original P9 form was a Single-Action (SA) model but production of this form only amounted to several hundred units - fewer than 500 in fact. This was followed by the more popular P9S which introduced a Double-Action (DA) system and went on to see strong market interest before the end.
The 9mm chambered model supported a 9-round magazine while the .45 ACP model used a 7-round magazine (single column stacking).
Operators of the P9 have included Algeria (Police), Argentina (Army), Greece, Japan (Special Forces), Lebanon, Malaysia (Police and Military), Netherlands (Special Forces), Paraguay, Portugal (National Guard), Saudi Arabia, Spain (Special Forces), Sudan, the United States (Navy), and West Germany (Police). The United States Navy took on a model supporting a sound suppressor for clandestine operatives.
Variants of the P9/P9S included the P9S "Target", a competition-minded pistol offering with additional sighting devices, adjustable trigger, and chambering in 9mm Parabellum or .45 ACP. The P9K ("Kurz") was a shortened version offering greater compactness. However, this model only ever existed in prototype form and was not entered into serial production.
An elegant-looking sidearm, the P9 still enjoys frontline use despite its Cold War-era roots.