The HK P9S is a military and police pistol using a unique breech locking system derived from Heckler & Koch’s highly successful G3 assault rifle.
Introduction
The HK P9S has been adopted by German armed forces and police forces and widely sold worldwide. Some have been manufactured in 7.65 mm Parabellum chambering and in .45 ACP chambering for export to the United States, but the 9 mm Parabellum version is the most common.
It was one of the first examples of a polymer-framed firearm. The lockwork was mostly stamped steel. The bolt and barrel were somewhat expensive to manufacture due to precision machining.
Unfortunately, it was introduced when high-capacity magazines were coming into vogue. It used a unique manual of arms that didn’t build conveniently on prior training. In a few years, Gaston Glock would design an even cheaper pistol for manufacturing.
Design
The roller locking system for the breach relies on a two-part breech block held close by two small rollers that engage in recesses in the barrel extension. The rollers are carried on the forward, lightweight portion of the block, which is the part of the slide.
When the pistol is fired, the light portion, impelled by the pressure on the cartridge case, attempts to move backward, but the inertia of the slide keeps the rollers forced outwards and the block section locked to the barrel.
As the inward pressure on the rollers, due to the pressure on the forward section of the block, gradually overcomes the inertia of the slide, so the bullet speeds up the barrel and leaves, allowing chamber pressure to drop to safe levels before the rollers move in and the slide and breech block assembly are free to move.
The HK P9S pistol has an internal hammer, with a protruding indicator pin at the frame’s rear, which extends when the hammer is cocked. A thumb-operated hammer releases and re-cocking lever on the left side, allowing the hammer to be lowered to a loaded chamber or rapidly cocked from the ‘down’ position.
The barrel has a ‘polygonal bore’ in which the four grooves (6in .45 ACP caliber) are merged into the rest of the bore so that the final result resembles a flattened circle. Heckler & Koch claim that this reduces friction and bullet deformation and promotes a somewhat higher velocity.
Variants
Two variant models exist: the HK P9, now discontinued, was the same pistol but with a conventional single-action lock; the HK P9S Sport Competition Model has a longer barrel with balanced weight, adjustable trigger stop, fine-adjustment rear sight, and an anatomical wooden grip.
The barrel is 5.5 in (140 mm) long, leading to a slight increase in muzzle velocity; with barrel counterweight fitted and a full magazine, it weighs 45.2 oz (1290 grams).
Technical specifications
| Manufacturer: | Heckler & Koch GmbH, D-7238 Oberndorf/Neckar, Germany |
| Type: | locked-breech double-action semi-automatic |
| Caliber: | 9 mm Parabellum |
| Barrel: | 4 inches (102 mm) |
| Weight (empty): | 30.8 oz (875 gm) with empty magazine |
| Capacity: | 9 rounds |
Of course there is a major user flaw in the P9 evident to many potential users. The slide mounted safety action is the reverse of frame mounted safeties that many in the US are used to. Down is Fire on 1911s and other Browning derivatives that have frame mounted safeties. Up is Fire down is safe in the P9.