Ordnance QF 17 pounder

Ordnance QF 17 pounder
17-pounder in Batey ha-Osef museum, Israel
Type	Anti-tank gun Tank gun
Place of origin	United Kingdom
Service history
In service	1943 -
Wars	World War II, Korean War
Production history
Designed	1941/42
Produced	1942-
Specifications
Weight	3 long tons (3.4 ST; 3.0 t)
Shell	76.2×583 mm. R
Calibre	3 inches (76.2 mm)
Barrels	13 ¾ ft (4.191 m., 55 calibres)
Carriage	Split trail carriage, with gunshield.
Elevation	-6° to +16.5°
Traverse	60°
Muzzle velocity	2,900 ft/s (884 m/s) HE, HEAT 3,950 ft/s (1,204 m/s) APDS

The Ordnance Quick-Firing 17 pounder (or just 17 pdr)^[1] was a 76.2 mm (3 inch) gun developed by the United Kingdom during World War II. It was used as an anti-tank gun on its own carriage, as well as equipping a number of British tanks. It was the most effective Allied anti-tank gun of the war. Used with the APDS shot it was capable of defeating all but the thickest armour on German tanks. It was used to 'up-gun' some foreign-built vehicles in British service, notably the Sherman Firefly, giving British tank units the ability to hold their own with their German counterparts. In the anti-tank role it was replaced by the 120 mm BAT recoilless rifle after the war. As a tank gun it was succeeded by the 20 pounder.

History

17-pounder, side view.

Before the QF 6-pounder had entered service, the British predicted that it would soon be inadequate given the increasing armour of German tanks. In late 1940 design of a replacement was started, and was largely complete by the end of 1941. A prototype production line was set up that spring, and with the appearance of Tiger I tanks in North Africa, the first 100 prototype 17-pdr anti-tank guns were quickly sent off to help counter this new threat. So great was the rush that they were sent before proper carriages had been developed, and the guns had to be mounted in the carriages of 25-pounder gun-howitzers. These early weapons were known as 17/25-pounders and given the codename Pheasant. They first saw action in February 1943. Fully developed 17-pdrs started production in 1943 and were first used during the Italian Campaign.

A Sherman Firefly with the 17 pounder

The 17-pdr outperformed all other Allied armour-piercing guns, and was quickly adapted for use on various tank chassis. However, few tanks were capable of carrying such a large gun due to the limitation of the size of their turret ring. It was expected that a 75 mm gun under development by Vickers would be used for tanks, but this did not enter service. The British had plans in hand for a tank - based on the Cromwell then under development - to carry the 17 pounder. However the problems inherent in the modifications meant the result, the Cruiser Mark VIII Challenger, was delayed and relatively few built.

However, the British devised a conversion for their US-supplied M4 Sherman tanks to take the 17 pounder and it was rushed into service in time for D-Day as the Sherman Firefly. The gun (a modified design was produced specifically for the Firefly) had to be rotated through 90 degrees to fit into the turret of the Sherman, i.e. it lay on its side, and an additional box was welded to the back of the turret to take the radio which was moved to allow for the breech and its recoil.^[2] More Shermans were converted until about 50% of Shermans in British service were Fireflies.

The British also converted some of their US-produced M10 tank destroyers, replacing the 3-inch (76 mm) cannon with the 17-pdr; the resulting vehicles were called Achilles or just 17 pdr M10.

The 17-pdr was also successfully fitted to the Australian-designed Sentinel tank during trials, though no Sentinels equipped with this gun entered service with the Australian Army.

The 17-pounder anti-tank guns saw action in Korea, against tanks and in general support use against bunker positions. Afterwards, it was largely replaced in the tank role by the Ordnance QF 20 pounder and in the anti-tank role by the 120 mm L6 WOMBAT recoilless gun.

The United States Army did not use the 17-pounder in action, though the gun was offered to US forces with a number of Shermans modified for testing.^[3]

Variants

Mark I

• first production versions.

Mark II

• intended for tank use. Removed the carrier mountings and replaced the muzzle brake with a counterweight. The brake was added back on in March 1944 with the introduction of the APDS shot. The Mk. II was used on the Archer tank destroyer and Challenger tank.

Mark III

• Royal Navy adaptation for use on landing craft, generally similar to the Mk. I, but included an automatic loading system. Unused.

Mark IV

• Another tank adaptation, this time with a different breech where the block slid to the side instead of down to take up less room. Unused.

Mark V

• A version of the Mk IV with different mounts to allow it to replace the US 3in (76.2mm) Gun M7 on the 3in SP, Wolverines, creating the 17pdr SP Achilles.

Mark VI

• Another Mk. IV adaptation with a shortened breech.

Mark VII

• Similar to the Mk. VI, yet another change to the breech.

Straussler Conversion

• This was an experimental gun, designed by Nicholas Straussler that was fitted with a motorized gun-carriage. A modified ammunition limber would be attached to the gun's trails, making a four-wheeled, self propelled vehicle and removing the need for a truck to tow the gun.^[4]

77 mm HV

• As the breech length of the 17-pdr was too long to fit in many tanks a new version was designed with a shorter breech, firing the same projectile as the 17-pdr from a 3-inch 20 cwt AA gun cartridge through a shortened 17-pdr barrel. This new gun's ammunition was not interchangeable with the 17-pounder, so to prevent confusion over ammunition supplies, it was renamed the "77 mm HV"—the 'HV' standing for High Velocity—although it was the same 76.2 mm calibre as the 17-pdr. This gun was used in the Comet tank.

Ammunition

The 17-pounder used two types of anti-tank ammunition. APCBC (Armour Piercing, Capped, Ballistic Capped) ammunition could penetrate 140 mm of armour at 457 metres and 131 mm at 914 m at a 30 degree angle. APDS (Armour Piercing, Discarding Sabot) could penetrate 208 mm of armour at 457 m and 192 mm at 914 m at a 30 degree angle,^[5][6][7] allowing it to penetrate the armour of even the redoubtable King Tiger tank. However, APDS was much less accurate than APCBC ammunition, and did not do nearly as much damage to an enemy tank if it did penetrate. APCBC ammunition was standard; APDS shot was used for about 6% of the average loadout of a 17-pdr equipped British tank.

The HE shell initially developed for the 17-pdr lacked power: due to the high-powered cartridge; the shell walls had to be thicker to stand the stresses of firing, leaving less room for explosive. Reducing the size of the propelling charge for the HE shell allowed the use of a thinner-walled and more powerful shell.

The 17-pdr produced a very large muzzle flash due to the large amount of propellant in its cartridges. Muzzle blast was also significant, described by crews of the anti-tank gun variant as resembling a hard slap on the chest.

Use

Anti-tank gun

The 17-pdr was a much bulkier and heavier weapon than its predecessor. As a result it had to be towed by a gun tractor such as the Crusader as it could not effectively be moved by its crew alone, especially on poor ground. After the war it was issued to anti-tank units of the Royal Artillery in the British Army of the Rhine (BAOR) towed by the M3 Half Track and when the Royal Artillery Anti-Tank Units were disbanded in 1951, transferred to Infantry battalions in the BAOR (6 per battalion), towed by the Windsor Tracked Carrier.

The complete AP round of a 17 pounder

25 pdr carriage

Stop gap measure named Pheasant.

Split trail carriage

• Split trail carriage, with gunshield.
• Weight: 3 t.
• Elevation: -6° to +16.5°
• Traverse: 60°

Vehicle mount

World War II

• Tank, Cruiser, Challenger (A30) - 200 built
• Tank, Cruiser, Comet I (A34) (77 mm OQF HV) - 1,200 by end of war.
• SP 17pdr, Valentine, Mk I, Archer tank destroyer built from Valentine tank hull. 655 built
• Sherman Firefly (Modified Sherman tank (Medium Tank M4) - about 2,000
• 17pdr SP Achilles (Modified 3in SP, Wolverine) - about 1,100 by end of war
• Tank, Infantry, Black Prince (A43) (prototype tank, never fielded)
• Australian Cruiser tank Mk IV (prototype turret only, never fielded)

Post-war

• Centurion - at prototype stage during war
• SP 17pdr, A30 (Avenger) - not available in time for war, 250 built

See also

• 7.5 cm Pak 40 : German equivalent anti-tank gun

Notes

1. ^ The British military often used the gun's projectile weight to denote different guns of the same calibre. Hence this was a 3-inch gun, of which there were several types in British service, which fired a projectile weighing approximately 17 pounds (7.7 kg)
2. ^ Being a long gun, in order to give a satisfactory balance more of the gun was mounted inside the turret
3. ^ SHERMAN M4 AND M4A3 17 POUNDER IN US SERVICE NEW INFORMATION
4. ^ Henry, Chris; Delft, Brian (2004). British Anti-tank Artillery 1939-45. Osprey Publishing. p. 18. ISBN 1841766380. 
5. ^ http://www.wwiiequipment.com/17pounder.aspx
6. ^ http://www.freeweb.hu/gva/weapons/british_guns5.html
7. ^ There is significant variation among sources regarding the performance of the APDS projectile. For example, a Bovington Tank Museum document states the 17-Pounder Mk II firing APDS could penetrate 187mm at 500 yards with a 30º angle of obliquity, while Jane's Armour and Artillery 1981-82 gives a penetration of 231mm at 1000 yards with the same strike angle.

External links

• Armor penetration table
• 17 Pounder development, production and ammunition data
• Data on British Second World War guns