Grossfuss Sturmgewehr

Grossfuss Sturmgewehr is classified as an assault rifle and firearm model developed during the final months of World War II. The project was led by designer Kurt Horn at the Grossfuss firm in Döbeln, an establishment previously recognised for its involvement in manufacturing the MG 42 machine gun. According to personal notes maintained by Horn, the Heereswaffenamt specified that the firearm must operate on the blowback principle, utilise the 7.92×33mm Kurz cartridge and magazines of the MKb 42(H), maintain a cyclic rate of fire of 500 rounds per minute, weigh no more than 4 kilograms, and match the barrel and overall length of the MKb 42(H). Because the intermediate 7.92×33mm Kurz round generated substantial pressure compared to pistol ammunition, a conventional blowback action would have required a bolt mass of approximately 1.5 kilograms, making the target weight unattainable.

To resolve this limitation, Horn engineered a gas-delayed blowback operating system, designated in German as the Gasdruckverschluss. High-pressure gas escaping from the chamber was directed into a cylinder to press against a piston jointed to the bolt, thereby retarding rearward bolt motion and allowing the bolt weight to be reduced to between 0.8 and 0.9 kilograms. The piston was connected at its rear to the receiver via a small return spring and exhibited a slight lateral deflection during rearward travel, allowing excess gas to vent once initial retardation was achieved. English Wikipedia records that Karl Barnitzke employed a similar gas-retardation concept in the Gustloff Volksturmgewehr (MP 507 or VG 1-5), but Barnitzke tapped gas from four small apertures near the muzzle, which proved far less efficient and required a heavier 1.4-kilogram bolt.

The Grossfuss weapon was designed for low-cost mass production, featuring stamped construction where only the barrel and bolt head required milling. Its iron sights were fixed to 300 metres, and firing modes were controlled by a three-way selector covering single shot, automatic fire, and safe position. Testing conducted by the Soviet Main Missile and Artillery Directorate (GAU) demonstrated high functional reliability, with one captured weapon firing approximately 1,900 rounds without stoppage and achieving accuracy comparable to the MP 43, despite a substantially shorter sighting line of 266 millimetres against 418 millimetres. Soviet evaluators noted that the dual horn-shaped cocking handles were unergonomic and liable to strike the shooter's hand during automatic fire, while also observing that manual cocking required an uncomfortably long draw from the prone position.

Discrepancies exist across historical literature regarding the physical existence, evaluation, and precise chronology of the Grossfuss Sturmgewehr. A 1958 technical publication issued by the United States Army Ordnance Corps reported that while the Grossfuss firm in Döbeln had designed a unique retarded blowback gas-actuated firearm, no physical specimens had ever been seen in the West. The Ordnance Corps text noted that the weapon was reportedly presented to the Speer Ministry Waffenkommission but had apparently never reached WaPrüf 2, the development and testing department of the Heereswaffenamt, while assigning its development period to late 1944 or early 1945. Structured authority records from Wikidata formally record the inception of the firearm model as 1945.

Contrary to the 1958 American assessment, documentation compiled by Soviet military authorities records that nine prototype rifles were captured by the advancing Red Army at the end of the war, five of which were recovered directly from the German testing ground at Kummersdorf. Soviet documentation designated these captured weapons as the Avtomat Horn. Soviet forces also secured technical blueprints and detained Kurt Horn himself, who was subsequently transferred to Factory Number 74 in Izhevsk—later known as Izhmash—alongside other German arms designers including Hugo Schmeisser. Soviet technical evaluations noted numerous dimensional variations between the recovered blueprints and the captured exemplars, indicating that the weapon was still undergoing active design adjustments when manufacturing ceased.

The total number of Grossfuss Sturmgewehr prototypes manufactured prior to the cessation of hostilities in 1945 is not established in surviving documentation. Differences in component dimensions between captured blueprints and physical exemplars, as documented in Soviet archival evaluations, confirm that design adjustments were still being actively made when production ended. Following the transfer of Kurt Horn and captured technical schematics to Factory Number 74 in the Soviet Union—where German designers including Hugo Schmeisser were retained—Soviet arms engineers evaluated the gas-delayed blowback concept for potential application in indigenous infantry weapons.

The mechanism directly informed Soviet experimental projects immediately after the conflict. Designer German A. Korobov, working at the Tula arms centre, adapted the gas-delayed blowback principle for his experimental TKB-454 assault rifle prototype. Outside of Soviet technical spheres, knowledge of the firearm remained restricted; as noted by the United States Army Ordnance Corps in 1958, no physical specimens had been examined in the West during the decade following the war. Today, only one physical weapon is recorded in public institutional holdings. A single, slightly incomplete prototype is preserved at the Military Historical Museum of Artillery, Engineers and Signal Corps in Saint Petersburg. The precise physical identification features and serial markings distinguishing individual experimental exemplars beyond the Saint Petersburg specimen are not established.