Dreyse/Rheinmetall submachine gun


This submachine gun was reportedly developed at Rheinmetall (whose armaments division was branded as Dreyse) at the end of World War I, although the associated patent is actually dated to October 1919. In any case, it was one of the earliest German SMG designs after those of Bergmann, Schwarzlose, and Walther. The Rheinmetall submachine gun utilized an interesting layout in which the return spring was situated inside the stock at a canted angle, and was connected by a rod to the rear of the bolt. Housing the return spring in the buttstock freed up space inside the receiver and allowed it to be reduced in length, as is evident from the initial patent sketches. The designer responsible for this system was the young Louis Stange, who would later become better known for designing the FG-42 machine gun in World War II.

Rheinmetall MP20
The Rheinmetall MP20, operating on the same principle as the Dreyse design.

By 1920, a prototype of the Rheinmetall submachine gun had been constructed, known as the MP20. It outwardly resembled the Bergmann M.P.18,I a great deal, with a jacketed barrel and a horizontally-feeding box magazine, but inwardly the return spring ran inside the stock as described. However, for some reason Stange did not take advantage of this to reduce the receiver length, and the MP20 was ultimately similar in dimensions to the M.P.18,I with a long tubular receiver; this may have been deliberately done to lengthen the bolt travel and thus reduce the fire rate. Development of the MP20 at Rheinmetall was brought to a sudden halt upon the enforcement of the Treaty of Versailles, which forbade the manufacture of most automatic weapons in Germany. Therefore Rheinmetall would outsource future development of this design to their subsidiary Solothurn in Switzerland, where it would eventually evolve into the highly renowned Steyr-Solothurn S1-100 submachine gun by 1929.

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