M1919 Browning machine gun
The M1919 Browning is a .30 caliber medium machine gun that was widely used during the 20th century, especially during World War II, the Korean War, and the Vietnam War. The M1919 saw service as a light infantry, coaxial, mounted, aircraft, and anti-aircraft machine gun by the U.S. and many other countries.
Source: Wikipedia — M1919 Browning machine gun (CC BY-SA 4.0)