Browning 0.50 M2 Machine Gun

This article deals with the Browning primarily as an aircraft and naval weapon. See the article on Small Arms for further discussion of the Browning as an infantry weapon.

Photograph of Browning 0.50 machine gun

U.S. Army


Specifications:


Bore
0.5"
12.7mm
Ammunition type     
AP, ball, incendiary, or tracer solid shot in 110-round belts

Weight of projectile     

1.6 ounce
45.4 gram

Velocity

2930 feet per second
893 meters per second

Range

7400 yards
6770 meters

Altitude

15,000 feet
4570 meters
Rate of fire 550-700 rounds per minute
Weight of gun
64 lbs
29 kg


The Browning 0.50 machine gun was a successful heavy machine gun design when used on land and in the air.  It traded a relatively low rate of fire for range, accuracy, and hitting power, having a significant armor piercing capability against aircraft armor and light Japanese tanks.  Both air-cooled and water-cooled versions were used on land.  Those mounted on aircraft were invariably air-cooled since the slip stream provided a highly efficient flow of air.

The M2 was developed in 1933 from the M1921 and revised in 1940 with a lighter barrel and double recoil springs that improved its nominal rate of fire. Its reliability steadily improved throughout the war, reaching a low of one jam per every 4000 rounds fired. The M3 was developed at the very end of the war and achieved a rate of fire of 1200 rounds per minute, a new record for a heavy machine gun. All versions were belt-fed.

The 0.50 round had a nominal penetration of 21 mm at normal impact at a range of 600 feet (183m). However, this dropped rapidly for oblique hits or if the bullet was subject to yaw. The typical penetration during air combat was 10-15 mm, which was normally still adequate.

Barrel wear was a significant problem for the aircraft version of the weapon, and aircrew were trained to fire no more than a 75 round initial burst and 25 round bursts thereafter. A longer burst would overheat the barrel, wear out the rifling, and destroy the accuracy of the gun. In January 1944, the U.S. Air Force adopted chromium alloy (Stellite) barrel liners that reduced wear and allowed much  longer bursts.

The Browning was much less successful as a naval antiaircraft gun and was replaced with 20mm Oerlikons as fast as these became available.  Its round was simply not heavy enough to do the job.  The weapon was more effective in its role as an antipersonnel weapon on submarines, PT boats, and other small craft.


References

Campbell (1985)
Williams and Gustin (2003)


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