The Browning M2 is an American-made heavy machine gun chambered in .50 BMG. It was designed towards the end of World War I by John Browning and has been in use with the armed forces of American and many other nations ever since. It is effective against infantry, unarmored or lightly armored vehicles and boats, light fortifications and low-flying aircraft. The M2 machine gun has been in production longer than any other machine gun in history.
The M2 is produced in a variety of different versions tailored to specific roles and mounts. It is most commonly used as a vehicle-mounted weapon, although man-portable versions designed to be fired by a team from a collapsible tripod also exist. By far the most common variant is the M2HB (heavy barrel), which replaced the water-cooled barrel jacket on the original model with a thicker, heavier barrel to help heat dissipation.