When mounted in a four-gun configuration, the M2 .50-cal. machine gun was known as the Quad-50, a highly effective anti-aircraft weapon in World War II. It was used extensively in Vietnam for antipersonnel purposes.
M51 Trailer-mounted Quad 50 of Battery C, 557th Antiaircraft Artillery (AAA) Automatic Weapons Battalion. In Europe during World Wwr II, this unit fought in the Battle of the Bulge in December 1944-January 1945. Photo is undated but appears to be from that time period.
M-51 and M-45/M-55 Quadruple .50-caliber Machine Guns
The standard .50-cal. Browning M2 machine gun ("Ma Deuce") was supplied with a variety of mounting systems, from a post or tripod to multiple mounts that fired two or more guns in tandem. The four-gun multiple mount was called the Quad-50. Use of the Quad 50 in World War II was primarily for anti-aircraft defense.
The M51 and M45/M55 mount were supplied on an M20 1-ton, 2 wheel trailer base, intended to be towed by a 2 1/2 ton truck. The gun mount, separate from the trailer, was also fitted to the M-16 Multiple Gun Motor Carriage, a halftrack to form a self-propelled unit and was used with other vehicles or stationary mounts. The heavier four-wheel trailer shown in the top photo was also supplied.
A single gunner operates the Quad-50, positioned in the middle of the mount. An electric trigger mechanism fires all four guns in tandem. The 'Tombstone' drum magazines (top photo and below) held 200 rounds each.
Following D-Day in June 1944, the M55, the quadruple .50-caliber machine guns on a trailer, were available in greater numbers than the M16 Multiple Gun Carriage halftrack with a mounted Quad-50. Since the M-55 trailer did not have as much mobility, the First Army obtained 700 excess halftracks, took the quad mounts off the M55s and bolted them to the halftracks creating a force of "M16B halftracks", as they were called. Other multiple mountings were used, such as the M33 twin mount utilized during WW II.
59th AAA Brigade Quad 50, Saipan, circa 1948.
In the period following World War II, the Quad 50 was utilized for anti-aircraft defense at U.S. bases around the world. The installation in Saipan (photo above) was a typical fixed defensive position for the Quad 50.
Use of the Quad-50 in Korea
Antiaircraft artillery detachment armed with Quad 50s, Suwon, Korea, June 1950.
Early in the Korean War the Quad-50 was still an effective anti-aircraft weapon. Until jet aircraft became common, the high rate of fire of the multiple .50 cal. guns was a good defense. In one of the first battles of the Korean War, at Suwon in June 1950, an antiaircraft artillery detachment armed with Quad 50s was airlifted from Japan, and became the first U.S. unit to mount an organized resistance to North Korea's invading forces (photo, above).
Quad-50s continued in use for their primary air defense mission, but also as infantry support against massed enemy formations and to thwart attacks, for the duration of the war.
The Quad-50 mount continued in service during the Vietnam War. They were used in semi-fixed locations to protect the perimeter of fire bases, but most famously they were mounted on the special gun trucks that protected convoys (photo above). The gun trucks were specially modified cargo trucks outfitted with armor and powerful weapons, often the Quad-50. Ambushes and roadblocks were effectively countered by the tremendous firepower of the Quad-50 system. A typical gun truck crew had six members, including driver, gunner, and loaders.
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