How a HK PSG1 works

This rifle is said to have been developed in response to the Munich massacre at the 1972 Summer Olympics. The West German police units at the time lacked the precision shooting capability to effectively neutralize the terrorists to prevent the hostages being killed. H&K was then commissioned to create a high-accuracy, large-magazine capacity, semi-automatic rifle for law enforcement and military use.

The PSG1 is mechanically based on the G3 rifle and features a low-noise bolt closing device (similar to the forward assist on many M16 rifles). Its shot-to-shot variation is expected to be better than 1 minute of angle (MOA) with match ammunition. This level of accuracy is only average compared to most modern bolt action sniper rifles, but is still exceptional for a semi-automatic rifle and at one time was claimed to be "one of the most accurate semi-automatic sniper rifles in the world.

PSG1s are not supplied with iron sights but come equipped with the Hensoldt ZF 6×42 PSG1 scope with an illuminated reticle. The scope has a built-in bullet drop compensation range adjustment feature which can be adjusted from 100 to 600 m.

It has a heavy free-floating barrel with polygonal rifling and an adjustable stock. The stock is of high impact matte black plastic and has a high degree of adjustment. It is adjustable for length, and includes a pivoting butt cap and a vertically-adjustable cheekpiece. The forend is fitted with a T-way rail for sling swivel or tripod.

The rifle also features a removable and adjustable trigger unit, for further individual fitting of the rifle. The trigger pull can be modified and the whole assembly is removable from the pistol grip. The pistol grip is of a target-style with an adjustable palm shelf.

The PSG1's official suppressor is from Brügger & Thomet (B and T).

The PSG1A1 variant was introduced by Heckler & Koch in 2006, and features two major improvements. First, the cocking handle was relocated a couple of degrees counter-clockwise. This was due to the fact that when locked rearward, it could physically interfere with the long scopes often used on the rifles. The second modification involved the replacement of the outdated Hensoldt scope. Non-police users often found the scope's 600 m range limitation and simple crosshairs inadequate for their needs. In addition, the rechargeable batteries are difficult to recharge and to find replacements. A final fault is that Hensoldt does not service the scope in the United States. For these reasons, the PSG1A1 has been outfitted with a Schmidt & Bender 3-12×50 Police Marksman II scope, mounted on 34 mm (1.3 in) rings. To remedy brass ejection a brass catcher must be installed.