9-mm pistol Hеckler und Koch P.7
At the end of 1974, the famous West German arms firm Hеckler& Koch GmbH (HK) in the city of Oberndorf am Neckar, has received an order for the creation of a police pistol, started designing a fundamentally new design of the gun. In 1976, the German police were submitted for testing 500 samples, and in 1979 began mass production of the gun, named HKP.7 or PSP (“police self-loading pistol”). 9-mm pistol P.7 was adopted by the police forces in Bavaria in July of that year. Pistols P.7 features high accuracy and little recoil, which was influenced by the low location of the fixed barrel.
This gun embodies many unusual for its time technical solutions. First of all, the barrel had polygonal barrel, in which there was neither field, nor rifling. In his channel there is a set screw faces slightly, giving the pool rotation.
Experience in the production of the previous gun VP.70 firms Hеckler& Koch showed that the weapons chambered for 9×19 “Parabellum” blowback does not enjoy the confidence of consumers, so the gunsmiths of Oberndorf returned to the semi-shutter, which managed to develop a completely new way of slowing down the opening of the valve, already previously used during the Second world war German gun maker V. Barnitzke in the construction of their weapons.
Automation of the new gun worked on the principle of using the recoil energy shutter with braking of powder gases bled from the barrel bore. At the bottom of the barrel just behind the chamber there was a vent hole. When fired some of the pressure of powder gases withdrawn through the hole in the barrel located under the cylinder, inside of which was the return spring and the piston rod fixed to the inner front portion of the casing-shutter. When fired, the powder gases into the cylinder through the exhaust aperture connecting the cylinder with the barrel; thus, the pressure in the chamber tending to push back and ejected the spent casing together with the bolt-casing, is balanced with pressure in the cylinder, through which the piston rod is subjected on the casing-gate, preventing his return. Thanks to this unlocking of the barrel did not occur until the bullet has left the barrel.