The MG 131 (shortened from German: Maschinengewehr 131, or "Machine gun 131") was a 13mm aircraft-mounted machine gun developed in 1938 by Rheinmetall-Borsig and produced from 1940-1945. The MG 131 was designed for use in fixed or flexible mounts (single or twin in the latter role) in Luftwaffe aircraft during World War II. At less than 60% the weight of the Browning M2 and using the significantly shorter 13x64mmB cartridge, it was the smallest and lightest of the aircraft heavy machine guns used by any nation during that conflict. This was a deliberate design decision in order to allow the weapon to directly replace the rifle-caliber MG 17 and MG 15, as a larger weapon would not fit in the same mountings. The MG 131 is also notable for using electric priming, rather than traditional percussion (firing pin) priming, allowing it to be more efficient when synchronized to fire through the propeller.
The Japanese produced a domestic copy as the Type 2 flexible-mounted machine gun, though as they could not manufacture the electrical primers it instead used standard percussion primers. As the Type 2 was only used in flexible defensive mounts, loss of benefit in terms of synchronization was moot.
The MG 131 and variants can be seen in the following films, television series, video games, and anime used by the following actors:
