M4 QUAD ANTI-AIRCRAFT GUN
A quad anti-aircraft machine gun ("complex machine gun"), developed by the team of N. F. Tokarev (son of F. V. Tokarev) in 1928-1931. The triple anti-aircraft machine gun of the 1931 model differed from the conventional Maxim machine gun of the 1910 model by the presence of a forced water circulation device and a larger capacity of machine gun belts - 500 rounds instead of the usual 250. Maxim machine gun systems have become the most common weapon of the army air defense.