DevelopmentThe weapon was developed as a private venture by the company in 1940 and was submitted to the Reichsluftfahrtministerium (RLM—Reich Aviation Ministry) in response to a 1942 requirement for a heavy aircraft weapon for use against the Allied bombers appearing en masse in German skies by then. Testing verified that the autocannon was well-suited to this role, requiring on average just four hits with high-explosive ammunition to bring down a heavy bomber such as a B-17 Flying Fortress or B-24 Liberator and a single hit to down a fighter. In comparison, the otherwise excellent 20 mm MG 151/20 required an average of 25 hits to down a B-17.
The MK 108 was quickly ordered into production and was installed in a variety of Luftwaffe fighter aircraft. It saw first operational service in late autumn 1943 with the Bf 110G-2 bomber destroyers and in the Bf 109G-6/U4.