Mauser Gerat 06 / Stg.45 assault rifle (Germany)

Mauser Gerät 06, an early roller-locked, gas-operated prototype dated to cicra 1943

Mauser StG.45(M), one of the very few pre-production rifles

Caliber: 7.92x33mm (7,92mm Kurz)
Action: delayed blowback
Overall length: 893 mm
Barrel length: 400 mm
Weight: 3.7 kg
Rate of fire: 400 rounds per minute
Magazine capacity: 10 or 30 rounds

German development of assault rifles did not stop with the adoption of the Haenel / Schmeisser "Sturmgewehr" Stg.44 rifle. The Stg.44 was far too heavy and, while being made mostly of stampings, still required plenty of raw materials. So, several German companies continued to produce 7.92 mm Kurz rifles of various designs. Most interesting among these was the Mauser design, usually credited to Wilhelm Stähle and Ludwig Vorgrimler. By 1943 Mauser Werke had developed a gas-operated weapon, which featured rigid roller locking broadly derived from MG 42 machine gun. This experimental weapon had a factory designation of “Gerät 06” (Device 06). This system (copied several times during the post-war period with equally unspectacular results) proved itself too complicated, but then the head of the analytical department at Mauser devised a version of the retarded (sometimes also called delayed) blowback system. In this system, there was no gas system and piston, and no rigid locking. Instead, rollers were used to retard the opening of the breech until the chamber pressure dropped down to safe levels. This system was factory designated as “Gerät 06H”, and by early 1945 was officially type-classified as Stg.45. It is believed that, no more than 30 specimens of these new weapons were made before Allied forces captured the Mauser Werke in Oberndorf, so it made no impact on the war. But, instead, it made significant impact on the post-war developments, since one of its designers, Ludwig Vorgrimler, went to France, where he continued to develop this design for several years. During the early 1950s he moved to Spain, where he participated in development of the CETME assault rifles, which led directly to the famous Heckler & Koch family of small arms, including the G3 and other assault rifles, submachine and machine guns, all featuring the same roller-delayed blowback system.

The famous Mauser Werke began to develop its own assault rifle by the 1943. It was decided to produce the cheapest possible deign, with as much stamping and welding used as possible. The original design, called “Gerät 06”, had a short-stroke gas piston and a locking system with two rollers, located in the bolt, which was forced out to the barrel extension to lock the bolt. When the gun was fired, the gas piston forced the bolt carrier back, and this withdrew the rollers from the cuts in the barrel extension, unlocking the bolt, and then pulling it back to eject the spent case and load a fresh round on its way back. This system was later found too complicated, and experiments proved that the locking system could be done away with since the rollers by themselves were able to retard the initial bolt movement, until the pressure in the chamber dropped down to a safe level. This improved system greatly simplified the design. This version was designated “Gerät 06H”. Because there was no primary extraction, a fluted chamber was devised to avoid sticking cases and subsequent torn rims and resulting jams. The receiver, as well as the round hand guards, was made from two stamped parts, left and right, connected by simple welding. The gun was built with a straight-line layout to reduce muzzle climb during automatic fire, so the sights were placed well above the barrel. This also resulted in the development of a shorter magazine with capacity of only 10 rounds, requested by the troops. The retarded-blowback Stg.45(M) were easily distinguishable from the original gas-operated “Gerät 06” rifles by the ribbed handguards of circular cross-section on the former, as opposed to the slab-sided handguards on the latter gun.
The Stg.45(M) was a good deal lighter than the Stg.44, and required about 50% less raw materials to make.