Ordnance QF 6 pounder

This article is about the World War II gun. For the 1880s naval gun and 1916 tank gun, see QF 6 pounder Hotchkiss. For the 1917 tank gun, see QF 6 pounder 6 cwt Hotchkiss.

Ordnance QF 6-pounder 7 cwt
QF 6 pounder at Batey ha-Osef
Type	Anti-tank gun
Place of origin	United Kingdom
Service history
In service	1942–1960
Used by	British Empire  United States  Ireland
Wars	World War II
Production history
Designed	1940
Produced	1941–1945
Specifications
Weight	2,520 lb (1,140 kg)
Barrel length	Mk II, III: 8 ft 4 in (2.54 m) 43 calibres Mk IV, V and M1: 50 calibres
Crew	6
Shell	57×441 mm. R
Calibre	2.24 in (57 mm)
Breech	vertical sliding block
Carriage	split trail
Elevation	-5° to +15°
Traverse	90°
Muzzle velocity	See Ammunition Table
Effective range	1,650 yd (1,510 m)
Maximum range	5,000 yd (4,600 m)
Sights	No.22c

The Ordnance Quick-Firing 6-pounder 7 cwt, or just 6 pounder, was a British 57 mm gun, their primary anti-tank gun during the middle of World War II, as well as the main armament for a number of armoured fighting vehicles. It was first used in North Africa in April 1942, and quickly replaced the 2 pounder in the anti-tank role, allowing the 25 pounder to revert to its intended artillery role. The United States Army also adopted the 6 pdr as their primary anti-tank gun under the designation 57 mm Gun M1.

Development and production

Development

A Canadian crew performing maintenance of the bore on the 6-pounder.

Limitations of the existing 2 pounders were apparent even as the gun was first entering service, and an effort was made to replace it with a much more capable weapon starting as early as 1938. The Woolwich Arsenal was entrusted with the development. The 57 mm calibre was chosen for the new gun. Guns of this calibre were employed by the Royal Navy from late 19th century, and therefore manufacturing equipment was available. The design was complete by 1940, but the carriage design was not completed until 1941.^{[citation needed]} The production was further delayed by the defeat in the Battle of France. The loss of equipment and the prospect of a German invasion made re-equipping the army with anti-tank weapons an urgent task, so a 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 acclimatization with the new weapon. 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, the new gun was mounted on a conventional two-wheeled split trail carriage. The first mass production variant—the Mk II—differed from the pre-production Mk I in having a shorter L/43 barrel, because of shortage of suitable lathes. The subsequent Mk IV was fitted with a L/50 barrel, with muzzle brake. Optional side shields were issued to give the crew better protection, but were apparently rarely used.

Although the 6 pounder was kept at least somewhat competitive through the war, the Army nevertheless started development of a more powerful weapon in 1942. Their 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. The program was eventually cancelled in January 1943.

Instead the 6 pounder was followed into production and service by the next generation British anti-tank gun, the 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 not only for the rest of the World War II, but also for some 20 years after the war.

A 57/42.6 mm squeeze bore adaptor was developed for the gun but was never adopted.

In addition to the UK, the gun was produced in Canada.

The Combined Ordinance Factories (COFAC) of South Africa produced three hundred examples as well.

U.S. production

The idea of manufacturing the 6 pounder in the U.S. was expressed by the U.S. Army Ordnance in February 1941. At that time the U.S. Army still favored the 37mm Gun M3 and production was planned solely for lend lease. The U.S. version, classified as substitute standard under the designation 57 mm Gun M1, was based on the 6 pounder Mk 2, two units of which were received from the UK. However since there was sufficient lathe capacity the longer barrel could be produced from the start.^[1] 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, i.e., the gun could be traversed by the crew pushing and pulling on the breech, instead of solely geared traverse, from September 1942. A more stable carriage was developed but not introduced. Once the 57 mm did enter US service a modified towing point design was introduced (the M1A3) but only for US use.

М1 production

Year	1942	1943	1944	1945	Total
Number produced	3,877	5,856	3,902	2,002	15,637

About one-third of production was delivered to the UK.

Like the British Army, the U.S. 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.

Service history

A 6-pounder anti-tank gun and its crew in action in the Western Desert, 3 November 1942

British service

The 6-pounders (and the U.S.-built M1, of which 4,242 pieces were received) were initially 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 airlanding battalion had an AA/AT company, with two four-gun AT platoons. The Far East theatres had lower priority and different organization, reflecting lower tank threat. The gun was also employed by Commonwealth forces, in formations similar to the British ones.

Initially 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, Ballistically Capped (APCBC) shot was supplied. A HE shell was produced so that the gun could be used against unarmoured targets as well.

British anti-tank gun QF 6pdr 7cwt Mk 2, Belgrade Military Museum, Serbia.

The 6-pounder first saw action in May 1942 at 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 enemy tanks in the action at 'Snipe' during the battle of Alamein. However, over the next year the Germans introduced much heavier designs into service, notably the Tiger I and Panther. The standard 6 pounder shot was effective frontally at short ranges as shown in the Armour plate experiment, but proved ineffective at extended ranges. It was the 6-pounder gun that accounted for the first Tiger destroyed in North Africa when mounted in the Churchill tank (which was the first western tank to knock out the Tiger I in tank vs tank combat).

The situation was somewhat improved by the development of more sophisticated ammunition, in form of the Armour-Piercing, Composite Rigid (APCR) shot, and the Armour-Piercing, Discarding Sabot (APDS) shot, which was available from 1944.

In the Royal Artillery regiments the 6-pounders were joined by the 17-pounders starting in 1943, but in infantry units the gun remained the sole AT gun in service until 1951, when it was finally declared obsolete and replaced with the 17-pounders in BAOR ( British Army of the Rhine).

U.S. service

57 mm Gun M1 firing at German bunker near Saint-Malo, Brittany.

In spring 1943, following the experience of the North African Campaign, the Infantry branch of the U.S. Army recognized the need to field a heavier antitank gun than the 37 mm M3. According to the Table of Organization and Equipment (TO&E) from 26 May 1943, a regiment antitank company included nine 57 mm guns and each battalion had an antitank platoon with three guns giving a total of 18 guns per regiment. Dodge WC-62 / WC-63 6×6 1½ ton trucks were issued as prime movers in place of the 3/4 ton truck used with its predecessor the 37mm. Introduction was made in the face of objections by the Infantry Board which believed it too heavy. The Ordnance Board on the other hand felt a more powerful weapon should be introduced. Airborne and Cavalry rejected it. By mid-1944 the M1 was the standard antitank gun of the U.S. infantry in the Western Front and outnumbered the M3 in Italy.

Because of the unexpected adoption for service, the only ammunition type in production in the U.S. by mid-1943 was the AP ammunition. Only after the Normandy Campaign did the HE round reach battlefield (U.S. units were sometimes able to get a limited amount of HE ammunition from the British Army), and the canister shot was not seen in significant numbers until the end of the war. This limited the efficiency of the gun in the infantry support role. Also, APCR or APDS rounds were never developed. Canister round production did not start until early 1945 and was also in limited use. Some British stocks of APDS were supplied to the US units.

The Airborne Command had rejected the 57 mm M1 in the summer of 1943 claiming its was unfit for airlanding by glider due to weight and the TO&E of February 1944 still had airborne divisions keeping their 37 mm guns. Nevertheless, the 82nd and the 101st airborne divisions were reequipped with British-manufactured 6 pounders on the narrow carriage Mk III designed for glider use - 24 in AA battalion, and 9 in glider infantry regiment - for the Normandy airdrops. Subsequently the guns were officially introduced under the TO&E from December 1944. According to the TO&E, a division was issued a total of 50 pieces: 8 in divisional artillery, 24 in AA battalion, and 18 in glider infantry regiment; parachute infantry regiments did not have anti-tank guns. The British guns were referred simply as 57 mm guns.

In the fighting after the Normandy landings the paratroops used them against German armour near St Mere Eglise and Carentan. However few tanks were encountered and they were mostly used for support which made the shortage of HE shell more significant. From July, US anti-tank units encountered the Panther tank which was only vulnerable to the 57 mm from the sides. Towed anti-tank guns were less effective in the hedgerow terrain where mobility suffered but when the Germans went on the offensive in August they were effective in defence with infantry. Towards the end of the war, towed anti-tank units were out of favour due to their lack of mobility compared to self-propelled guns and the 57mm was used by infantry battalions. However with few tanks to contend with some units that would have been equipped with the 57mm were instead deployed as rifle companies or only with the Bazooka.^[2]

The M1 went out of service in the U.S. soon after the end of the war.

Other operators

In addition to being used by the U.S., British and commonwealth forces, the M1 was supplied under the lend lease program to the Free French Forces (653), USSR (400) and Brazil (57).

The Royal Navy used the 6-pounder extensively in Motor Gunboats during World War II (especially the 'D' type). The gun was mounted on a hydraulic powered mount and fitted with the Molins power loading system, permitting a 6-round burst at 1 round per second. The guns were all the early short-barrel (43 calibre) type, and fired exclusively HE ammunition, at much lower muzzle velocities than for AP.

The Israel Defense Forces employed the 6-pounder in 1950s in brigade-level anti-tank battalions and battalion-level anti-tank platoons (the latter formations were disbanded in 1953). By late 1955, Israel Defense Forces possessed 157 pieces and 100 more were purchased from the Netherlands in 1956, too late to enter service before the Suez Crisis. Some of those are described as "57-mm guns, nearly identical to the 6-pounders and firing the same ammunition", which apparently makes them U.S.-built M1 guns.^[3]

The gun was also used by the Pakistani Army; numerous examples can still be seen as 'gate guards' outside army bases in Pakistan.

The Irish Army acquired six 6 pounder anti-tank guns in the late 1940s.

Modern day use

The U.S. 57 mm M1 gun is popular with modern-day cannoneers, as there is a relatively good supply of shell casings and projectiles.

The gun is also reportedly still in active military use with some South American countries and, in coastal defense emplacements, outlying island garrisons of the Republic of China Army.

Variants

External images
	Sketch of the 6-pounder Mk 2. [1]
	6-pounder Mk IV in action in Normandy. [2]
	57 mm M1 of the 44th Infantry Division in France, 1944. [3]
	M1 in a street of Rimschweiler, Germany. [4]
	57 mm GMC T49. [5]

• Mk 1: limited production version with L/50 barrel.
• Mk 2: first mass production version. Shortened L/43 barrel was adopted due to the shortage of suitable manufacturing equipment.
• Mk 3: tank version of Mk 2.
• Mk 4: L/50 barrel, single baffle muzzle brake.
• Mk 5: tank version of Mk 4 .
• Molins Class M gun: 6 pounder gun fitted with automatic loader built by the Molins company, a manufacturer of cigarette making machines. It was mounted on the Royal Navy Motor Torpedo Boats and in the RAF Mosquito planes, which were referred to as the "Tsetse". Reports of use in a limited number of Royal Navy Escort Destroyers ("V and W" class vessels) in a twin mounting at "A" gun position appear to be confusion with the use of the 6 Pdr 10 Cwt 'Twin Six' Coastal Gun in that position.
• 57 mm Gun M1: U.S. built version; although based on Mk II, it had the "original" L/50 barrel.

Carriage types, British:

• Mk 1
• Mk 1A: different axle and wheels
• Mk 2: simplified design
• Mk 3: modified for use by airborne troops

Carriage types, U.S.:

• M1
• M1A1: U.S. wheels and tyres
• M1A2 (1942): improved traverse mechanism, allowing free traverse
• M1A3 (1943): modified towing hook; the first version to be adopted by the U.S. Army
• M2 (1944): caster wheel added to the right trail, relocated trail handles, new utility box
• M2A1 (1945): improved elevation gear

A T48 57 mm Gun Motor Carriage in front of the Polish Army Museum.

Self-propelled mounts

Tank gun versions of the 6-pounder were used in Crusader III, Cavalier, Centaur I and II, Cromwell I to III, Valentine VIII to X and Churchill III and IV, and also in the Canadian Ram Mk II and the experimental American Light Tank T7E2. The Deacon and the experimental Alecto Mk II self-propelled guns also mounted the 6-pounder. Another experimental vehicle armed with the 6-pounder was a Firefly tank destroyer, based on the Morris Light Reconnaissance Car.^[4]

The only mass-produced vehicle mounting the 57 mm M1 was the M3 Half-track based 57mm Gun Motor Carriage T48 (also known by its Soviet designation SU-57). The production of the T18E2 armored car, also known as Boarhound, was stopped after 30 units were built. A project of tank destroyer armed with the M1—the 57 mm Gun Motor Carriage T49—was cancelled after a single pilot vehicle was built. Similarly, the wheeled 57 mm Gun Motor Carriage T44, based on Ford 4×4 ¾ ton cargo carrier chassis, was cancelled after a brief testing.

Ammunition

Available ammunition^[5]

Type	Model	Weight kg (lb)	Filler	Muzzle velocity, m/s (L/43 guns)	Muzzle velocity, m/s (L/50 guns)
British ammunition
AP	Shot, AP, Mks 1 to 7	2.86 (6.3)	-	853	892
APC (from September 1942)	Shot, APC, Mk 8T[6]	2.86 (6.3)	-	846	884
APCBC (from January 1943)	Shot, APCBC, Mk 9T	3.23 (7.1)	-	792	831
APCR (from October 1943)	Shot, APCR, Mk 1T	1.90 (4.2)	-		1,082
APDS (from March 1944)	Shot, APDS, Mk 1T	1.42 (3.1)	-		1,219
HE[7]	Shell, HE, Mk 10T	approx. 3 (6.6)			820
U.S. ammunition
AP	AP Shot M70	2.85 (6.3)	-		853
APCBC/HE	APC Shot M86	3.30 (7.3)	Dunnite, 34 g		823
HE (authorized in March 1944)	HE Shell T18 / M303
Canister (in production from January 1945)	Canister Shot T17 / M305

See also

• 6 pounder 6 cwt AA gun
• 6 pounder 10 cwt Naval and Coastal defence gun
• List of U.S. Army weapons by supply catalog designation (SNL C-36)
• British standard ordnance weights and measurements

Notes

1. ^ Zaloga US Anti-tank Artillery Osprey p13
2. ^ Zaloga p40
3. ^ When the Engines Roared.
4. ^ Henry, Chris (2004). New Vanguard 98 British Anti-tank Artillery 1939-45, Osprey Publishing ISBN 1-84176-638-0
5. ^ There were also practice rounds and blank rounds
6. ^ Together with different combinations of propelling charge these were Cartridges Mark IT through to Mark IVT and "HV" cartridges IT and IIT
7. ^ "HE Shell Mk I, foil" and "HE Shell Mk IIT, foil" using the Mk IM case

References

• Chamberlain, Peter; Terry Gander (1974). Anti-Tank Weapons. WWII Fact Files. Arco Publishing Company, New York. ISBN 0-668-03505-6. 
• Fletcher, David (1983). Cromwell Tank: Vehicle History and Specifications. The Tank Museum. HMSO. ISBN 0 11 290403 3. 
• Hogg, Ian V. (1998). Allied Artillery of World War Two. Crowood Press, Ramsbury. ISBN 1-86126-165-9. 
• Hunnicutt, R. P. (1992). Stuart: A History of the American Light Tank.. Presidio Press. ISBN 0-89141-462-2. 
• Hunnicutt, R. P. (2002). Armored Car: A History of American Wheeled Combat Vehicles.. Presidio Press. ISBN 0-89141-777-X. 
• When the Engines Roared: 50th Anniversary to the Sinai War (ברעום המנועים: 50 שנה למלחמת סיני ). Ministry of Defence, Israel. 2006. ISBN 965-05-1337-X. 
• Zaloga, Steven J. (2005). US Anti-tank Artillery 1941-45. New Vanguard 107. illustrated by Brian Delf. Osprey Publishing. ISBN 1-84176-690-9. 
• Zaloga, Steven J. (2007). US Airborne Divisions in the ETO 1944-45. Battle Orders 25. Osprey Publishing. ISBN 1-84176-118-2. 

External links

• Development, Performance, Production of the 6pdr AT Gun
• Anthony G Williams - The 6 pdr 7cwt and the Molins gun
• US M-1 57 mm Anti-tank gun at Militaria: Weapons
• Armour penetration table
• Photo gallery at Tanxheaven.com
• [6] TO&E antitank company