Ordnance QF 17 pounder

Gun development

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, the design of a replacement began, and was largely completed by the end of 1941. A prototype production line was set up in spring 1942, and with the appearance of Tiger I tanks in early 1943 in the North African Campaign, the first 100 prototype 17-pounder anti-tank guns were quickly sent 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-pounders started production in 1943 and were first used during the Italian Campaign. They became one of the most effective weapons on the battlefield, on both carriages and tanks.

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

Adaptation into tanks and AFVs

The 17-pounder 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 size limitations of their turret rings. A new British tank specification, A29, was produced to meet the need for a 17-pounder armed cruiser tank. While the A29 was eventually cancelled without a successful design being produced, an amended specification, A30, reached production in 1943. The A30 specification reduced weight and enabled the use of Cromwell tank components as a design expedient. The resulting Cruiser Mark VIII Challenger had a longer hull and provided a larger turret, allowing the 17-pounder to be mounted along with space for a second loader, thought to be required for the gun's larger ammunition. However, production of the tank took time and few could be completed before the allied invasion of Normandy.

While developing the Challenger tank, the British devised a conversion for their US-supplied M4 Sherman tanks to mount the 17-pounder. This was applied in sufficient numbers to put them into service in time for D-Day as the Sherman Firefly. The gun, a modified design that was produced specifically for the Firefly, was rotated through 90 degrees to mount into the turret of the Sherman, i.e. it lay on its side. 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. Production of the Challenger was cancelled, and 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) gun with the 17-pounder; the resulting vehicles were called 17pdr SP Achilles or just 17-pdr M10. These served with Royal Artillery as self-propelled guns.

The 17-pounder was also successfully trialled on the Australian-designed Sentinel tank, though no Sentinels equipped with this gun entered service with the Australian Army.

A variant of the 17-pounder, the 77mm HV, was used on the Comet tank. A separate weapon, this fired 17-pounder projectiles in a more tank-compatible form, and ultimately replaced the need for 17-pounder tanks late in the war.

As the war came to a close, the 17-pounder was also deployed on the Centurion tank, until ultimately being replaced by the 20-pounder.

The United States Army did not use the 17-pounder, though the gun was offered to US forces with a number of Sherman tanks modified for testing. US tanks began to use the 76 mm gun M1 instead.

Variants

77 mm HV

The British started work on developing a gun that was small enough to fit on their tank designs—particularly the Cromwell cruiser tank then at the design stage. It was intended to fire the US 75 mm projectiles (AP shot and HE) at a higher velocity, avoiding a downgrade in armour penetration versus the 6-pounder, which the dual purpose 75mm was replacing.

The new 50-calibre long gun, known as the Vickers HV 75 mm, fired a 75mm projectile attached to a necked down 3-inch (76.2 mm) 20 cwt AA gun cartridge through a modified breech. The larger 3" cartridge provided a greater propellant charge compared with normal 75mm shells. Although the 75 mm HV was a promising weapon, it proved to be too big for the Cromwell tank, which was ultimately fitted with the normal QF 75 mm gun in use on other British tanks. To account for this difference, tank squadrons were teamed with Challenger and Sherman Firefly tanks armed with the 17-pounder.

When the Cromwell's replacement, the Comet, was at the design stage, the 75 mm HV concept was reworked to fire the same projectiles as the 17-pounder through a shortened 17-pounder barrel, but retaining the 3-inch cartridge case firing from a standard 3-inch breech.

This has the benefit of greater ease of use on tanks, many of which would not have sufficient turret space to accommodate the breech length and recoil distance of the 17-pounder. Similarly, the smaller 3" based ammunition was more easy to store and handle in the tank's cramped interior.

This new gun's ammunition was not interchangeable with the 17-pounder, however, and 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-pounder.

This gun was used in the Comet tank.

Ammunition

The 17-pounder used two types of anti-tank ammunition. Armour Piercing, Capped, Ballistic Capped (APCBC) ammunition could penetrate 163 mm of armour at 500 metres and 150 mm at 1000 m. The Armour-piercing discarding sabot (APDS) could penetrate 256 mm of armour at 500 m and 233 mm at 1000 m, and allowing it in theory to penetrate the armour of even the German King Tiger heavy tank.

However, the smaller (sub-calibre) tungsten core of APDS was considered to provide less accurate fire than APCBC ammunition at ranges beyond 500 yards. This was due to the much lesser visible impact of rounds that fell short, making it hard to spot the fall of shot and correct aim. The APDS was also considered to cause less damage to an enemy tank if it did penetrate the armour, but the sub-calibre tungsten steel core tended to destabilise after penetrating armour and ricochet around inside the target, causing crew casualties. APCBC ammunition was standard; APDS shot was used for about 6% of the average load of a 17-pounder-equipped British tank. Most sources agree that APDS was not available on D-Day itself, but reached Normandy in increasing amounts by the end of June or early July 1944. It was available for the breakout battle from Normandy and the advance to the Netherlands and Germany.

The HE shell initially developed for the 17-pounder 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-pounder 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.

Performance

Anti-tank gun

The 17-pounder 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 Morris Quad, M3 Half-track or the Crusader, as it could not effectively be moved by its gun crew alone, especially on poor ground. After firing on soft ground, the 17-pounder frequently had to be pulled out of the ground due to the gun recoil burying the trail spades. After the Second World 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. When the Royal Artillery anti-tank units were disbanded in 1951, it was transferred to Infantry battalions in the BAOR (six per battalion), towed by the Oxford Tracked Carrier. It was later replaced by the 120 mm BAT recoilless rifle anti-tank weapon.

Stop gap measure named Pheasant.

Middle East

In the immediate post-war era in the Middle East, armies of Arab nations - Transjordan, Egypt, Syria and Iraq - used mostly British manufactured artillery including the towed 17-pounder. The Israelis used a number of 17 pounders they captured from the Arabs in the war of independence

Vehicle mount