Ordnance QF 6 pounder

From Wikipedia, the free encyclopedia

Ordnance QF 6-pounder 7 cwt
QF 6 pdr at Batey ha-Osef
Type	anti-tank gun
Place of origin	United Kingdom
Service history
In service	1942-1960
Used by	British Commonwealth, United States
Wars	WW2
Production history
Designed	1940
Specifications
Weight	1,140 kg / 2,520 lb
Length	2.82 m
Barrel length	Mk II, III: 43 calibres Mk IV, V and M1: 50 calibres
Crew	6

Shell	57x441R
Calibre	2.24 in (57 mm)
Breech	vertical block
Carriage	split trail
Traverse:	90 degrees
Maximum range	5,000 yards (4,600 m)

QF 6 pounder anti-tank gun in Batey ha-Osef museum, Israel.

The Ordnance QF 6-pounder 7 cwt, or just "6 pdr", 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 US Army also adopted the 6 pdr as their primary anti-tank gun under the designation 57mm Gun M1.

1 Development and production
- 1.1 Development
- 1.2 US production
2 Service history
3 Modern day use
4 Variants
5 Self-propelled mounts
6 Ammunition
7 See also
8 References
9 External links

[edit] Development and production

[edit] Development

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 for the new gun. Guns of this calibre were employed by the Royal Navy from late 19th century, and therefore a 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 shorter L/43 barrel, because of shortage in suitable lathes. The subsequent Mk IV was fitted with 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 pdr of 59 calibre length, but this version proved too heavy to be used in the same role as the 6 pdr. 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.

[edit] US production

The idea of manfacturing the 6 pounder in the US was expressed by the US Army Ordnance in February 1941. At that time the US Army still favoured the 37mm Gun M3 and production was planned solely for lend lease. The US version, classified as substitute standard under the designation 57mm Gun M1, was based on the 6 pounder Mk 2, two units of which were received from the UK, but unlike the Mk II had the original long barrel. Production started early in 1942 and continued until 1945.

М1 production, pcs.
Year	1942	1943	1944	1945	Total
Produced, pcs.	3,877	5,856	3,902	2,002	15,637

Like the British Army, the US Army also experimented with a squeeze bore adaptor (57/40mm T10), but the program was abandoned.

[edit] Service history

Polish paratroopers (1st Independent Parachute Brigade) manhandling 6 pdr AT gun.

[edit] British service

The 6-pounders (and the US-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 represented by a basic Armour-Piercing (AP) shot, but by January 1943 an Armour-Piercing, Capped (APC) shot and an Armour-Piercing, Capped, Ballistically Capped (APCBC) shots were supplied. A HE shell was produced so that the gun could be used against unarmoured targets as well.

The 6-pounder easily dealt with contemporary enemy tanks, but over the next year the Germans introduced much heavier designs into service, notably the Tiger I and Panther. The standard 6 pounder shot was insufficient against the front armour of these new designs, but it was still effective against them from other angles. In fact, it was the 6-pounder gun that accounted for the first Tiger destroyed in North Africa.

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. The latter was particularly succesfull giving the gun the capability to knock out a Tiger 1, head on at 1,000 meters.

In the Royal Artillery regiments the 6-pounders were gradually replaced by the 17-pounders starting in 1943, but in infantry units the gun remained in service until 1960, when it was finally declared obsolete.

[edit] US service

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

In spring 1943, following the experience of the North African Campaign, the Infantry branch of the US Army recognized the need to field a heavier antitank gun than the 37mm M3. According to the Table of Organization and equipment from 26 May 1943, a regimental antitank company included nine 57mm guns and each battalion had an antitank platoon with three guns giving a total of 18 guns per regiment. Dodge WC-62 / WC-63 6x6 1 1/2 ton trucks were issued as prime movers. By mid-1944 the M1 was the standard antitank gun of the US 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 US by mid-1943 was the AP ammunition. Only after the Normandy Campaign did the HE round reach battlefield (US 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.

The US Army also employed a limited number of British-built 6-pounders on carriage Mk 3, designed to fit into the Horsa glider. These guns were used to replace 37 mm pieces in the 82nd and the 101st airborne divisions before the Normandy airdrops.

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

[edit] Other operators

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

Israel employed the 6-pounder in 1950s in brigade-level anti-tank battalions and batttalion-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 US-built M1 guns.

[edit] Modern day use

The U.S. 57mm 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.

[edit] Variants

External images
	Sketch of the 6-pounder Mk 2. [1]
	6-pounder Mk IV in action in Normandy. [2]
	57mm M1 of the 44th Infantry Division in France, 1944. [3]
	M1 in a street of Rimschweiler, Germany. [4]
	57mm 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 gun - 6 pounder gun fitted with automatic loader built by the Molins company, a manufacturer of cigarette vending machines. Was mounted on the Royal Navy Motor Torpedo Boats, a limited number of Royal Navy Escort Destroyers ("VW" class vessels in a twin mounting at "A" gun position) and in the RAF Mosquito planes, which were then referred to as "Tsetse".
57mm Gun M1 - US built version; although based on Mk II, it had the "original" L/50 barrel.

Carriage types, British:

Mk 1
Mk 1A - different axle and whells
Mk 2 - simplified design
Mk 3 - modified for use by airborne troops

Carriage types, US:

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

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

[edit] 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.

The only mass-produced vehicle mounting the 57mm M1 was the M3 Half-track based 57mm Gun Motor Carriage T48 (also known by its Soviet designation SU-57). A project of tank destroyer armed with the M1 - the 57mm Gun Motor Carriage T49 - was cancelled after a single pilot vehicle was built.

[edit] Ammunition

Available ammunition
Type	Model	Weight, kg	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	-	853	892
APC (from September 1942)	Shot, APC, Mk 8T	2.86	-	846	884
APCBC (from January 1943)	Shot, APCBC, Mk 9T	3.23	-	792	831
APCR (from October 1943)	Shot, APCR, Mk 1T	1.90	-		1,082
APDS (from March 1944)	Shot, APDS, Mk 1T	1.42	-		1,219
HE	Shell, HE, Mk 10T	approx. 3			820
US ammunition
AP	AP Shot M70	2.85	-		853
APCBC/HE	APC Shot M86	3.30	Dunnite, 34 g		823
HE (authorized in March 1944)	HE Shell T18 / M303
Canister (in production from Jan. 1945)	Canister Shot T17 / M305

[edit] See also

6 pounder 6 cwt AA gun
6 pounder 10 cwt Naval gun

[edit] References

Hogg, Ian V. - Allied Artillery of World War Two - Crowood Press, Ramsbury, 1998, ISBN 1-86126-165-9.
Chamberlain, Peter and Gander, Terry - Anti-Tank Weapons, Arco Publishing Company, New York, 1974 (WWII Fact Files), ISBN 0-668-03505-6.
Zaloga, Steven J., Brian Delf - US Anti-tank Artillery 1941-45, Osprey Publishing 2005 (New Vanguard 107), ISBN 1-84176-690-9.
Hunnicutt, R. P. - Stuart: A History of the American Light Tank., Presidio Press 1992, ISBN 0-89141-462-2.
When the Engines Roared: 50th Anniversary to the Sinai War, MoD 2006 (ברעום המנועים: 50 שנה למלחמת סיני - משרד הבטחון הוצאה לאור 2006, ISBN 965-05-1337-X)