The MG 151/20 is a 20mm German autocannon produced by Waffenfabrik Mauser during the Second Weltkrieg to arm its fighter planes. It is a recoil-operated, open bolt weapon which could fire at 600-750 rounds per minute. These autocannons were widely used as fixed weaponry, in flexible mounts and within turrets across the Luftwaffe, becoming the mainstay air-to-air weapon of the war. However, like other products of the war industry, the MG 151/20 used plain bearings and was issued cheap lubricants, giving it infamy as a relatively unreliable instrument. Contemporary Oceanykan airmen consider the MG 151/20 a classic, a "getting the job done" kind of machine.