|Region of Origin:||Nazi Germany|
460 m (500 yd)
|Rate of Fire:||700–750 rounds/min|
Contracts for rifles firing the 7.92x33mm round were sent to both Walther and Haenel (whose design group was headed by Hugo Schmeisser), who were asked to submit prototype weapons under the name Maschinenkarabiner 1942 (MKb 42, literally "machine (ie. fully automatic) carbine"). Both designs were similar, using a gas-operated action, with both semi-automatic and fully automatic firing modes.
The original prototype of Haenel's design, the MKb 42(H), fired from an open bolt and used a striker for firing. The receiver and trigger housing with pistol grip were made from steel stampings, which were attached to the barrel assembly on a hinge, allowing the weapon to be folded open for quick disassembly and cleaning. The Haenel design proved superior to Walther's MKb 42(W), and the army then asked Haenel for another version incorporating a list of minor changes designated MKb 42(H). One was to include lugs for mounting a standard bayonet, another to change the pitch of the rifling. A production run of these modified versions was sent to the field in November 1942, and the users appreciated it with a few reservations. Another set of modifications added a hinged cover over the ejection port to keep it clean in combat, and rails to mount a telescopic sight. A run of these modified MKb 42(H)s in late 1942 and early 1943 produced 11,833 guns for field trials.
Ultimately it was recommended that a hammer firing system operating from a closed bolt similar to Walther's design be incorporated. The gas expansion chamber over the barrel was deemed unnecessary, and was removed from successive designs, as was the underbarrel bayonet lug.