that the gun could be traversed by the crew pushing and pulling on the breech, instead of solely geared traverse, from September 1942. The M1 was made standard issue in the Spring of 1943. A more stable carriage was developed but not introduced. Once the 57 mm entered US service, a modified towing point design was introduced (the M1A3) for US use. Tractors for the M1 included the Dodge WC-63 1½-Ton 6×6 and the M2 Half-Track. Two-thirds of American production (10,000 guns) went to US Army Divisions in Europe. About one-third of production (over 4,200 guns) was delivered to the UK and 400 guns were sent to the Soviet Union through Lend-Lease. When the United States re-armed and re-equipped Free French forces for the Normandy landings, their anti-tank units received American-made M1s. Like the British Army, the US Army also experimented with a squeeze bore adaptor (57/40 mm T10) but the program was abandoned. American shell designs and production lagged behind the introduction of the gun once it was accepted for service and so, at first, only AP shot was available. The HE shell was not available until after the Normandy landings and UK stocks were procured to cover its absence. Its use by regular US Army front-line units was discontinued in the 1950s. Service history British service Anti-tank gun The 6-pounders (and the US-built M1 of which 4,242 guns were received) were issued to the Royal Artillery anti-tank regiments of infantry and armoured divisions in the western theatres (four batteries with 12 pieces each) and later in the war to the six-gun anti-tank platoons of infantry battalions. An air-landing battalion had an AA/AT company with two four-gun AT platoons. The Far East theatres had lower priority and different organisation, reflecting the lower tank threat. The gun was also employed by Commonwealth forces in formations similar to the British. The anti-tank ammunition was a basic Armour-Piercing (AP) shot, but by January 1943 an Armour-Piercing, Capped (APC) shot and an Armour-Piercing, Capped, Ballistic Capped (APCBC) shot was supplied. A High Explosive shell was produced for use against unarmoured targets. The 6-pounder first saw action in May 1942 at the Battle of Gazala. It made an immediate impact on the battlefield as it was able to penetrate any enemy tank then in service. In the most celebrated action, the 6-pounder guns of 2nd Battalion, The Rifle Brigade (together with part of 239