How a HK P7 Pistol Works

Wikipedia: The Heckler & Koch P7 is a German 9×19mm semi-automatic pistol designed by Helmut Weldle and produced from 1979 to 2008 by Heckler & Koch GmbH (H&K). It was revealed to the public for the first time in 1976 as the PSP (Polizei-Selbstlade-Pistole—"police self-loading pistol").The P7M13, a variant of the P7 with a double-stack magazine, was produced until 2000, and was unsuccessfully submitted to the U.S. Army XM9 pistol trials as a replacement for the M1911 pistol.

The P7 is a semi-automatic blowback-operated firearm. It features a unique gas-delayed blowback system modeled on the Swiss Pistole 47 W+F (Waffenfabrik Bern) prototype pistol (and ultimately on the Barnitzke system first used in the Volkssturmgewehr 1-5),which used gas pressures from the ignited cartridge and fed them through a small port in the barrel (in front of the chamber) to retard the rearward motion of the slide. This is accomplished by means of a piston contained inside a cylinder located under the barrel that opposes the rearward motion of the slide until the gas pressure has declined—after the bullet has left the barrel—hence allowing the slide to end its rearward motion, opening the breech and ejecting the empty cartridge case.

The chamber has 18 flutes that aid in the extraction process by allowing combustion gases to flow between the fired case and the chamber walls, preventing the case from "sticking" to the chamber walls. The drawback of this system is that the breech "opens" slightly prematurely to allow the slide to initiate its rearward motion. The high temperature gases cycling through a tube located below the chamber area and above the trigger made the early versions of this pistol uncomfortable, according to some, to shoot after the content of two magazines were fired due to heating. The advantages of this system are a simpler manufacturing process due to the absence of a locking system and a high mechanical accuracy due to the barrel being fixed in the frame; the barrel does not execute any sort of lateral or vertical movement during the operating cycle as with the Browning cam-action systems common to many other locked breech pistols.

Type Semi-automatic pistol
Place of origin West Germany
Service history
Used by See Users
Production history
Designer Helmut Weldle
Designed 1976
Manufacturer Heckler & Koch
Produced 1979–2008
Variants See Variants
Specifications
Mass PSP: 785 g (27.7 oz)
P7M8: 780 g (28 oz)
P7M13: 850 g (30 oz)
P7K3: 775 g (27.3 oz) (.22 LR) / 760 g (27 oz) (.32 ACP) / 750 g (26 oz) (.380 ACP)
P7M10: 1,250 g (44 oz)
P7PT8: 720 g (25 oz)
Length PSP: 166 mm (6.5 in)
P7M8, P7PT8: 171 mm (6.7 in)
P7M13, P7M10: 175 mm (6.9 in)
P7K3: 160 mm (6.3 in)
Barrel length PSP, P7M8, P7M13, P7M10, P7PT8: 105 mm (4.1 in)
P7K3: 96.5 mm (3.8 in)
Width PSP, P7M8: 29 mm (1.1 in)
P7M13, P7M10: 33 mm (1.3 in)
P7K3: 29 mm (1.1 in)
Height PSP: 127 mm (5.0 in)
P7M8: 129 mm (5.1 in)
P7M13: 135 mm (5.3 in)
P7M10: 145 mm (5.7 in)
P7K3: 125 mm (4.9 in)
Cartridge PSP, P7M8, P7M13: 9×19mm Parabellum
P7K3: .22 Long Rifle, .32 ACP, .380 ACP
P7M10: .40 S&W
P7PT8: 9×19mm PT
P7M7: .45 ACP (prototype only)
Action PSP, P7M8, P7M13, P7M10: Gas-delayed blowback
P7K3, P7PT8: Straight blowback
Muzzle velocity PSP, P7M8, P7M13: 351 m/s (1,152 ft/s)
P7K3: 275 m/s (902.2 ft/s) (.22 LR) / 330 m/s (1,082.7 ft/s) (.32 ACP) / 305 m/s (1,000.7 ft/s) (.380 ACP)
P7M10: 300 m/s (984.3 ft/s)-345 m/s (1,131.9 ft/s)
P7PT8: ~410 m/s (1,345.1 ft/s)
Feed system PSP, P7M8, P7K3, P7PT8: 8-round box magazine
P7M13: 13-round box magazine
P7M7: 7-round box magazine
P7M10: 10-round box magazine
Sights Front blade, rear notch
148 mm (5.8 in) sight radius.