The MG 131 was an air-cooled heavy machine gun that fired the heavy 13 x 64B mm cartridge, and could be used as an infantry machine gun, but was primarily used as a aircraft weapon. Measuring 117 centimeters long, which included the 55 centimeter long barrel, the MG 131 weighed 16.6 kilograms, and had a rate of fire of 900 rounds per minute.
The MG 131 was one of a number of weapons fitted with the Solothurn lock, consisting of a rotating collar fitted around the barrel extension, locking this to the bolt by means of an uninterrupted thread. As the barrel/bolt assembly moves rearward, the collar is rotated by cams in the receiver, disengaging the lock and enabling the lock to be separated. The MG 131 could fire rounds at velocity of 750 meters per second.
The armor piercing version of the 13 x 64B cartridge, as used by the MG 131, had a low armor penetration of 100 mm at 100 meters, with an impact angle of 60 degrees. At a distance of 300 meters, penetration dropped to 7.8 mm at the same angle.[N 1]
From 1941 the MG 131 was used by bombers to replace the MG 15 in flexible mountings, for which it was fitted with a pistol grip and conventional trigger, and in a neat, low-profile powered turret.[N 2] Syncronized versions of the MG 131 were also fitted inside the cowlings of fighters, beginning in 1943 with the Messerschmitt Bf 109 G-6 and Focke-Wulf Fw 190A-7, replacing the older 7.92 mm MG 17.
- ↑ By comparison, the best 7.92 x 57 AP loading for the MG 17, the S.m.K-v, fired at the same angle, could penetrate 8 mm at 100 meters and 6 mm at 300 meters.
- ↑ Twin and quadruple turrets were also developed, but these saw little or no use.
- ↑ Williams, Anthony G. Rapid Fire - The Development of Automatic Cannon, Heavy Machine Guns and their Ammunition for Armies, Navies and Air Forces. Airlife Publishing. 2000. ISBN 1-84037-122-6 Page 237
- ↑ Williams, Anthony G. Page 55
- ↑ 3.0 3.1 Williams, Anthony G. Page 165
- ↑ Williams, Anthony G. Page 166
- ↑ Williams, Anthony G. Page 172