Ordnance QF 75 mm
Encyclopedia
The Ordnance QF 75 mm, abbreviated to OQF 75 mm, was a British
tank-gun of the Second World War. It was used instead of the Ordnance QF 6 pounder
("6 pdr"), an anti-tank gun, to give better performance against infantry targets in a similar fashion to the 75 mm gun fitted to the American Sherman tank. The QF came from "quick-firing". The gun was also sometimes known as ROQF from Royal Ordnance (the manufacturer) Quick-Firing.
, and then the larger QF 6 pdr
, that fired Armour Piercing shot - good against tanks but ineffective against groups of infantry. Some tanks operating in the infantry support role were given guns firing HE shells, e.g. early models of Churchill tank
and CS ("Close Support") versions of the Matilda II
. The decision to equip British tanks with an HE shell firing gun for "soft" targets like infantry and, importantly, anti-tank guns was taken by the War Office
.
An HE shell for the 6 pounder was in production by the time of the start of the Tunisia Campaign
and available in large amounts in the Italian Campaign
. However, the round lacked sufficient explosive power. The power of the US 75 mm HE round used in the M3 75 mm
was found to be markedly superior, and a number of Churchills in operation in Italy had guns scavenged from Sherman tanks and fitted to their turrets to give the Churchill NA75 (NA coming from "North Africa" where the conversions were carried out). Approximately 200 were converted in this way.
Instead of looking to take the American gun to be fitted en masse into modified British tanks, the Royal Ordnance modified their 6 pdr design by boring out the barrel and adapting the breech to fire the US round. The resulting gun could then be fitted without redesigned tank mountings. It was effective but although gaining a good HE shell they had an inferior anti-tank round and this proved troublesome against the minority of heavily armoured German tanks. In the Battle of Villers-Bocage
Cromwell tank
s with the 75 mm were outgunned by Tiger tanks
of the 101st SS Heavy Tank Battalion.
Though the 75 mm had a good HE shell, it was still thought that a more powerful close support weapon was needed and as such the Ordnance QF 95 mm howitzer was agreed for a limited number of tanks.
tanks. The weapon was used in Italy and Normandy
Invasion (and possibly in Burma
against the Japanese) until the end of the war. While the 75 mm was a conversion from the 6 pounder
, some units retained a number of 6 pounder gunned tanks, due to its superior anti tank firepower over the 75 mm, especially as the 6 pounder could use the even more effective APCR and APDS
rounds.
Externally the gun was nearly identical to the 6 pounder gun. The 14.9 lb (6.76 kg) HE shell fired at 2,050 ft/s (625 m/s) was found to be the best available - superior to that of the 6 pounder, M7 3 in
and 17 pounder
all chiefly anti-tank guns. However, against armour its AP shell was the worst, penetrating only 68 mm of RHA
at 500 yards (460 m) and a 30 degree angle of attack, whereas the AP shells of the others penetrated between 57 mm and 76 mm in Normandy during 1944. The AP shell for the 75 mm gun was a 15 lb (6.8 kg) projectile with a couple of ounces (60 g) of HE filling propelled by a 2 lb (900 g) charge to 2,000 feet per second (610 m/s). In British service the AP shell was used without its explosive filling and as such was referred to as "AP Shot M61".
s used by the British forces received the designation Ordnance QF 75 mm Mk I. And in the early part of the Second World War some American 75 mm Gun M1897A3 field guns were purchased from the US. These were referred to as Ordnance 75 mm.
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
tank-gun of the Second World War. It was used instead of the Ordnance QF 6 pounder
Ordnance QF 6 pounder
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...
("6 pdr"), an anti-tank gun, to give better performance against infantry targets in a similar fashion to the 75 mm gun fitted to the American Sherman tank. The QF came from "quick-firing". The gun was also sometimes known as ROQF from Royal Ordnance (the manufacturer) Quick-Firing.
Development
Prior to the introduction of the ROQF 75 mm, British tanks had been equipped with guns such as the QF 2 pounderOrdnance QF 2 pounder
The Ordnance QF 2-pounder was a British anti-tank and vehicle-mounted gun, employed in the Second World War. It was actively used in the Battle of France, and during the North Africa campaign...
, and then the larger QF 6 pdr
Ordnance QF 6 pounder
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...
, that fired Armour Piercing shot - good against tanks but ineffective against groups of infantry. Some tanks operating in the infantry support role were given guns firing HE shells, e.g. early models of Churchill tank
Churchill tank
The Tank, Infantry, Mk IV was a heavy British infantry tank used in the Second World War, best known for its heavy armour, large longitudinal chassis with all-around tracks with multiple bogies, and its use as the basis of many specialist vehicles. It was one of the heaviest Allied tanks of the war...
and CS ("Close Support") versions of the Matilda II
Matilda tank
The Infantry Tank Mark II known as the Matilda II was a British infantry tank of the Second World War. It was also identified from its General Staff Specification A12....
. The decision to equip British tanks with an HE shell firing gun for "soft" targets like infantry and, importantly, anti-tank guns was taken by the War Office
War Office
The War Office was a department of the British Government, responsible for the administration of the British Army between the 17th century and 1964, when its functions were transferred to the Ministry of Defence...
.
An HE shell for the 6 pounder was in production by the time of the start of the Tunisia Campaign
Tunisia Campaign
The Tunisia Campaign was a series of battles that took place in Tunisia during the North African Campaign of the Second World War, between Axis and Allied forces. The Allies consisted of British Imperial Forces, including Polish and Greek contingents, with American and French corps...
and available in large amounts in the Italian Campaign
Italian Campaign (World War II)
The Italian Campaign of World War II was the name of Allied operations in and around Italy, from 1943 to the end of the war in Europe. Joint Allied Forces Headquarters AFHQ was operationally responsible for all Allied land forces in the Mediterranean theatre, and it planned and commanded the...
. However, the round lacked sufficient explosive power. The power of the US 75 mm HE round used in the M3 75 mm
75 mm Gun (US)
The US 75 mm gun tank gun M2 and the later M3 were the standard American tank guns of the Second World War.Besides use on the two main American medium tanks of the war the M3 Lee and the M4 Sherman . The lightweight M6 and M5 variants were developed to equip the Light Tank M24 and the B-25...
was found to be markedly superior, and a number of Churchills in operation in Italy had guns scavenged from Sherman tanks and fitted to their turrets to give the Churchill NA75 (NA coming from "North Africa" where the conversions were carried out). Approximately 200 were converted in this way.
Instead of looking to take the American gun to be fitted en masse into modified British tanks, the Royal Ordnance modified their 6 pdr design by boring out the barrel and adapting the breech to fire the US round. The resulting gun could then be fitted without redesigned tank mountings. It was effective but although gaining a good HE shell they had an inferior anti-tank round and this proved troublesome against the minority of heavily armoured German tanks. In the Battle of Villers-Bocage
Battle of Villers-Bocage
The Battle of Villers-Bocage took place during the Second World War on 13 June 1944, one week after the Allies landed in Normandy to begin the liberation of German-occupied France. The battle was the result of a British attempt to improve their position by exploiting a temporary vulnerability in...
Cromwell tank
Cromwell tank
Tank, Cruiser, Mk VIII, Cromwell ,The designation as the eighth Cruiser tank design, its name given for ease of reference and its General Staff specification number respectively and the related Centaur tank, were one of the most successful series of cruiser tanks fielded by Britain in the Second...
s with the 75 mm were outgunned by Tiger tanks
Tiger I
Tiger I is the common name of a German heavy tank developed in 1942 and used in World War II. The final official German designation was Panzerkampfwagen Tiger Ausf. E, often shortened to Tiger. It was an answer to the unexpectedly formidable Soviet armour encountered in the initial months of...
of the 101st SS Heavy Tank Battalion.
Though the 75 mm had a good HE shell, it was still thought that a more powerful close support weapon was needed and as such the Ordnance QF 95 mm howitzer was agreed for a limited number of tanks.
Ammunition
The QF 75mm used US ammunition. The shells were "fixed" ammunition, the shell cartridge and projectile being proved together as a single complete round.- Shell HE M46full name for the round was "Shell, fixed, HE M48, normal charge" followed by the fuze specification with either the M48 or M54 fuze
- Bursting charge was 1.49 lb TNT or 1.36 lb 50/50 AmatolAmatolAmatol is a highly explosive material made from a mixture of TNT and ammonium nitrate. Its name originates from the words ammonium and toluene...
or 1.52 lb trimonite.80% ammonium nitrate, 10% TNT, 10% aluminium The M48 fuze could be set for impact detonation ("Superquick") or delayed detonation; when in "Superquick" setting the delay would set the shell off if the impact didn't set off fuze. The M54 round had variable delay; the fuze starting burning at the instance of firing the round.- Shot APC M61, with tracer in the base
- A armour-piercing capped projectile with a thin ballistic cap ("windshield") for better aerodynamics.
- Shot AP M72, with tracer in the base
- an entirely solid projectile
Service
The ROQF 75 mm was chiefly used on the Churchill and CromwellCromwell tank
Tank, Cruiser, Mk VIII, Cromwell ,The designation as the eighth Cruiser tank design, its name given for ease of reference and its General Staff specification number respectively and the related Centaur tank, were one of the most successful series of cruiser tanks fielded by Britain in the Second...
tanks. The weapon was used in Italy and Normandy
Operation Overlord
Operation Overlord was the code name for the Battle of Normandy, the operation that launched the invasion of German-occupied western Europe during World War II by Allied forces. The operation commenced on 6 June 1944 with the Normandy landings...
Invasion (and possibly in Burma
Burma Campaign
The Burma Campaign in the South-East Asian Theatre of World War II was fought primarily between British Commonwealth, Chinese and United States forces against the forces of the Empire of Japan, Thailand, and the Indian National Army. British Commonwealth land forces were drawn primarily from...
against the Japanese) until the end of the war. While the 75 mm was a conversion from the 6 pounder
Ordnance QF 6 pounder
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...
, some units retained a number of 6 pounder gunned tanks, due to its superior anti tank firepower over the 75 mm, especially as the 6 pounder could use the even more effective APCR and APDS
APDS
APDS may refer to:*Armour-piercing discarding sabot*Androgynous Peripheral Docking System*Augusta Preparatory Day School...
rounds.
Externally the gun was nearly identical to the 6 pounder gun. The 14.9 lb (6.76 kg) HE shell fired at 2,050 ft/s (625 m/s) was found to be the best available - superior to that of the 6 pounder, M7 3 in
3-inch M1918 gun
The 3-inch M1918 gun was a United States 3-inch anti-aircraft gun that entered service in 1918 and served until it was finally superseded by the 90 mm M3 gun just prior to the opening of World War II...
and 17 pounder
Ordnance QF 17 pounder
The Ordnance Quick-Firing 17 pounder was a 76.2 mm 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...
all chiefly anti-tank guns. However, against armour its AP shell was the worst, penetrating only 68 mm of RHA
Rolled homogeneous armour
Rolled homogeneous armour is a type of steel which is used to armour vehicles.-Composition:Armoured steel must be hard yet impervious to shock in order to resist high velocity metal projectiles. Steel with these characteristics is produced by processing cast steel billets of appropriate size and...
at 500 yards (460 m) and a 30 degree angle of attack, whereas the AP shells of the others penetrated between 57 mm and 76 mm in Normandy during 1944. The AP shell for the 75 mm gun was a 15 lb (6.8 kg) projectile with a couple of ounces (60 g) of HE filling propelled by a 2 lb (900 g) charge to 2,000 feet per second (610 m/s). In British service the AP shell was used without its explosive filling and as such was referred to as "AP Shot M61".
| Gun | Shell weight | Muzzle velocity | Muzzle energy | ||
|---|---|---|---|---|---|
| (lb) | (kg) | (ft/s) | (m/s) | (kJ) | |
| 2 pdr | 2 | 0.9 | 2,650 | 810 | 295 |
| 6 pdr AP shot |
6 | 2.8 | 3,000 | 910 | 1,100 |
| 75 mm | 14.9 | 6.8 | 2,050 | 620 | 1,300 |
| 17 pdr | 17 | 7.7 | 2,950 | 900 | 3,100 |
Similar named guns
In the First World War some French 75 mm field gunField gun
A field gun is an artillery piece. Originally the term referred to smaller guns that could accompany a field army on the march and when in combat could be moved about the battlefield in response to changing circumstances, as to opposed guns installed in a fort, or to siege cannon or mortars which...
s used by the British forces received the designation Ordnance QF 75 mm Mk I. And in the early part of the Second World War some American 75 mm Gun M1897A3 field guns were purchased from the US. These were referred to as Ordnance 75 mm.
See also
- M3 75 mm /40,
- M7 76.2 mm3-inch M1918 gunThe 3-inch M1918 gun was a United States 3-inch anti-aircraft gun that entered service in 1918 and served until it was finally superseded by the 90 mm M3 gun just prior to the opening of World War II...
, - 90 mm M3 gun,