The Ordnance quick-firing 6-pounder 7 cwt,British forces traditionally denoted smaller ordnance by the weight of its standard projectile, in this case approximately . The approximate weight of the gun barrel and breech, "7 cwt" (cwt = hundredweight), was included in the designation to distinguish this gun from others also firing a 6 lb projectile. or just 6-pounder, was a British 57 mm gun, serving during the Second World War as a primary anti-tank gun of both the British and United States Army (as the 57 mm gun M1). It was also used as the main armament for a number of armoured fighting vehicles.
Although designed before the start of the war, it did not reach service until the North African Campaign in April 1942, where it replaced the 2-pounder as an anti-tank gun, allowing the 25-pounder gun-howitzer to revert to its intended artillery role.
Development and production
Development
Limitations of the existing 2-pounders were apparent even as the gun entered service in 1938. An effort was made to replace it with a much more capable weapon starting that year.
The Woolwich Arsenal was entrusted with the development of a new gun with a calibre of 57 mm. Guns of this calibre had been employed by the Royal Navy from the late 19th century and manufacturing equipment was available. The gun design was complete by 1940 but the carriage design took until 1941. The production was further delayed by the defeat in the Battle of France. The loss of equipment – most of the heavy equipment of the British Expeditionary Force (BEF) was left behind in France during Operation Dynamo – and the prospect of a German invasion made re-equipping the army with anti-tank weapons an urgent task. The decision was made to carry on the production of the 2-pounder, avoiding the period of adaptation to production and also of re-training and acclimatisation with the new weapon. It was estimated that 100 6-pounders would displace the production of 600 2-pounders.Postan, British War Production From Dunkirk to Pearl Harbor (part of the History of the Second World War) page 194 This had the effect of delaying production of the 6-pounder until November 1941 and its entry into service until May 1942.
Unlike the 2-pounder, which was mounted on a 360-degree traverse, the new gun was mounted on a conventional two-wheeled split trail carriage on pneumatic tyres but without a spring suspension. The first mass production variant, the Mk II, differed from the pre-production Mk I in having a shorter L/43 barrel, because of the shortage of suitable lathes. The Mk IV was fitted with an L/50 barrel, with muzzle brake. Optional side shields were issued to give the crew better protection but were apparently rarely used.
The 6-pounder was used where possible to replace the 2-pounder in British tanks, requiring work on the turrets, pending the introduction of new tanks designed for the 6-pounder. The Churchill Marks III and IV, Valentine Mark IX and Crusader Mark III all began to enter service during 1942. The Valentine and Crusader both needed to lose a crew member from the turret. Tanks designed to take the 6-pounder were the troubled Cavalier, the Cromwell and the Centaur. When the Cromwell went into combat in 1944, it was armed with the Ordnance QF 75 mm gun, which was a redesign of the 6-pounder to take US 75 mm ammunition which made it more useful against general targets. The 6-pounder was also fitted to the AEC armoured car Mark II.
Although the 6-pounder was kept at least somewhat competitive through the war, the Army started the development of a more powerful weapon in 1942. The aim was to produce a gun with the same general dimensions and weight as the 6-pounder but with improved performance. The first attempt was an 8-pounder of 59 calibre length but this version proved too heavy to be used in the same role as the 6-pounder. A second attempt was made with a shorter 48 calibre barrel but this proved to have only marginally better performance than the 6-pounder and the program was cancelled in January 1943.
The 6-pounder was followed into production by the next generation British anti-tank gun, the Ordnance QF 17-pounder, which came into use from February 1943. As a smaller and more manoeuvrable gun, the 6-pounder continued to be used by the British Army for the rest of World War II and for about 20 years afterwards. A 57/42.6 mm squeeze bore adaptor was developed for the gun but was never adopted. The gun was also produced in Canada and South Africa, where the Combined Ordnance Factories (COFAC) produced 300.
Production +Production of gunsBoyf, David "The 6 Pounder Anti-Tank Gun" wwiiequipment.comYear19411942194319441945Number20117,85416,5861,964 -
US production +М1 production Year 1942 1943 1944 1945 Total Number produced 3,877 5,856 3,902 2,002 15,637 The idea of manufacturing the 6-pounder in the US was expressed by US Army Ordnance in February 1941. The US Army still favoured the 37mm gun M3 and production was planned solely for lend lease. The US version, classified as substitute standard as 57 mm gun M1, was based on the 6-pounder Mark II, two units of which were received from the UK. Since there was sufficient lathe capacity, the longer barrel could be produced from the start. Production started early in 1942 and continued until 1945. The M1A1 variant used US combat tyres and wheels. The M1A2 introduced the British practice of free traverse, meaning 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 American units, while about one-third (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, so 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 Anti-Tank Battery Royal Artillery under command), destroyed more than 15 Axis tanks in the action at Outpost Snipe during the Second Battle of El Alamein. Over the next year, the Germans introduced much heavier tanks into service, notably the Tiger I. The standard 6-pounder shot was ineffective against the front armour at any range but proved effective on the less armoured sides and rear.
6-pounder gunfire accounted for the first Tigers disabled in North Africa; two Tigers being knocked out by towed 6-pounder AT guns, while the 48th Royal Tank Regiment knocked out the first Tigers by the Western Allies in tank vs. tank action with their Churchill tanks, destroying two Tiger I (the same unit also knocked out the first Panther tanks by the Western Allies in May 1944 in Italy). The North Irish Horse disabled and captured Tiger 131 after the crew had abandoned it after it received several hits, most seriously a shot which struck the turret ring, making traverse impossible. The situation was somewhat improved by the development of more sophisticated ammunition in the form of the Armour-Piercing, Composite Rigid (APCR) shot and the Armour-Piercing, Discarding Sabot (APDS) shot, which was available from 1944 and made it effective against the frontal armour of Tiger Is and Panthers.
In the Royal Artillery regiments, the 6-pounders were joined by the 17-pounders starting in 1943; in infantry units, the gun remained the sole AT gun in service until 1951, when it was finally declared obsolete and replaced by the 17-pounder in the British Army of the Rhine (BAOR).
Tank gun The first tanks to go into action armed with the 6-pounder gun were the Crusader Mk III and the Churchill Mark III, both initially with the short barrel 6-pounder Mk III. Churchill Mk III saw action in the Dieppe Raid of August 1942. Six Churchills deployed to North Africa, as KingForce, were used in action at El Alamein in October, destroying five tanks and three AT guns for the loss of one Churchill. The Crusader Mk III served with the armoured regiments of 8th Army, and later with 1st Army when they landed in Tunisia. The 6-pounder was initially chosen for the A24 Cavalier, A27M Cromwell and A27L Centaur, all similar designs in competition to replace the Crusader. In 1943 a program was initiated to replace the 6-pounder with the Ordnance QF 75 mm, a dual role weapon with better HE performance. By 1944 only the Churchill Mk III and Mk IV still mounted the 6-pounder Mk V gun and these were able to take advantage of the new APDS round which could penetrate 140mm of armor at 1,000 yards. This ammunition was used in the N.W. Europe Campaign and in Italy.
Molins gun
The Royal Navy used the 6-pounder extensively in Motor Gun Boats during World War II (especially the Fairmile D). The gun was mounted on a hydraulic-powered mount and fitted with a power loading system developed by the Molins Machine Company Limited, permitting a six-round burst at one round per second. The guns were all the early short-barrel (43 calibre) type and fired exclusively HE (high-explosive) ammunition, at much lower muzzle velocities than for AP (armour-piercing), because of the use of flashless propellant for night operations. The naval designation was QF 6-Pounder Mk IIA; nearly 600 of these weapons were made.