SD:AB M1 Gun 57mm

 is a United States Anti-tank unit.

Overview
The Ordnance QF 6-pounder 7 cwt anti-tank gun was developed by the United Kingdom in response to the limitations of existing 2-pounder guns. The gun itself was fully designed as early as 1940, although the carriage wasn't completed until a year later, while delays in starting production pushed back its entry into service to May 1942. The result was a flexible, powerful anti-tank gun that could effectively fight German tanks of the time and became the primary British anti-tank gun of World War II.

The gun was adopted by US Army infantry units as 57 mm Gun M1, after the North African campaign demonstrated the need for a more powerful anti-tank gun. Both the Cavalry and Airborne units rejected the design, the former due to its firepower, the latter due to its weight. However, the 101st and 82nd Airborne divisions went against the grain, choosing British-manufactured 6-pounders on the lightweight Mk III carriage for deployment via gliders during the invasion of Normandy.

These 6-pounders were used in the A, B and C  Anti-Tank Batteries of  81st Airborne Anti-Aircraft Battalion. These batteries were originally equipped with AB M3 Gun 37mm but were reequipped with M1 57mm Anti Guns then to airborne six ponders guns since the British gun were designed for glider use.

377th Parachute Field Artillery Battalion is also equipped with Antiaircraft and Antitank Battery which equipped with two Platoons each of four .50-cal M2 heavy machine guns and two Platoons each of two 57-mm antitank guns.