QF 4.7 inch Mark XI gun

QF 4.7 inch Mark XI
Forward turrets on HMS Matchless
Type	Dual-purpose gun
Place of origin	United Kingdom
Service history
In service	1941-1970
Used by	Royal Navy Turkish Navy
Wars	World War II Korean War
Production history
Designed	1937–39?
Number built	87
Specifications
Weight	3.351 long tons (3,405 kg)
Length	247.7 in (6.29 m)
Barrel length	Bore: 236.2 in (6.00 m) L/50 (cal)

Shell	Separate-loading
Shell weight	62 pounds (28.1 kg) SAP or HE
Calibre	4.7 inches (120 mm)
Breech	Semi-automatic horizontal sliding-block
Recoil	Hydro-pneumatic
Elevation	-10° to +50°
Rate of fire	10 rounds per minute
Muzzle velocity	2,538 ft/s (774 m/s)
Maximum firing range	21,240 yards (19,420 m) at 45°

The 4.7 inch QF Mark XI^{[Note 1]} was a 120-mm 50-calibre naval gun deployed on Royal Navy (RN) and allied destroyers during World War II.^[1]

Description and history

The QF 4.7-inch Mk XI gun, on the Mk XX twin mounting, was introduced to the RN aboard the L and M class destroyers, in commission from 1941 onwards. It featured a 62 lb (28.1 kg) shell fired at 2538 ft/second (774 m/s) to a maximum range of 21,240 yards (19,420 m) at 45 degrees of elevation.^[1] The Mk XX mounting was fully enclosed, but the hoists did not revolve with the turret. The gun's firing cycle was six seconds^[2]^[3] and the separate shell and cordite hoists for each gun provided shells and cartridges at a rate of 10 per minute. The shells and cartridges were transferred from the hoists to the tilting tray of the fuze-setting machine by hand. Once the fuzes were set, they slid forward to the loading tray from which they were rammed forward into the breech by a hydraulic rammer.^[4] The horizontal sliding-block breech opened semi-automatically after the guns fired.^[1]

The guns could be loaded at any angle of elevation. The Mk XX mounting could elevate to a maximum of 50° and depress to −10°. The turret had a maximum powered training rate of 10° per second, but was manually elevated. Including the crew and ammunition, the revolving weight of the mounting was 37.363 long tons (37.963 t). It was protected by a gun shield .25 inches (6.4 mm) thick.,^[2] too thin to hold a direct hit, but still appreciable versus small splinters, explosions, small caliber rifles.

With a shell 24% heavier, the new gun was far more powerful than the previous 45 calibre long 4.7 inch gun making it a match for a weapon such as the Italian 120/50 mm,^[5] whilst also improving the air defence role. It could now penetrate 3 inches (76.2 mm) of armour at a range of 10 km rather than 5.9 km. In the Battle of Pantelleria on 15 June 1942), HMS Marne and Matchless engaged a superior Italian task force. Marne fired 704 shells, Matchless 746, while HMS Ithuriel (with four 4.7 /45) managed to fire only 246. Marne hit with a single shell the cruiser RN Eugenio di Savoia at around 5.50 AM. Matchless failed to hit the other cruiser, RN Montecuccoli, but later hit the large destroyer Ugolino Vivaldi. The new 120/50 mm shell was heavy and powerful, and the Italian destroyer was soon laying dead in the water, with a furious fire at midship. That destroyer was saved only towing her to a near naval base, where the fire was finally extinguished.^[6]

In the words of Tony di Giuliano, the 120/50 Mark XI gun was the perhaps the finest destroyer gun made by British during the World War II, but it was also heavy and costly, as were the ships equipped with it. Wartime production required a much greater production of ships and guns, so cheaper weapons were installed in many other classes, like the 'O' and 'P' (102 mm) and furthers (with the old 120 mm), until the 114 mm (4.5 in) started to replace them, as the first, powerful dual purpose destroyer gun.

Notes

↑ Mark XI = Mark 11. Britain used Roman numerals to denote Marks (i.e. models) of ordnance until after World War II. Hence this article covers the eleventh model of British QF 4.7-inch gun.

Footnotes

1 2 3 Campbell, p. 46
1 2 Campbell, p. 47
↑ March, p. 507:
"The guns in the Mk XI mounting in the "L"s fired 12 rounds per minute, as each shell or cartridge was taken from the top of the hoist another automatically took its place."
↑ Smith, p. 206
↑ italian 120/50 guns
↑ Cernuschi, p. 10-12

References

Campbell, John (1985). Naval Weapons of World War II. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-459-4.
Hodges, Peter; Friedman, Norman (1979). Destroyer Weapons of World War 2. London: Conway Maritime Press. ISBN 0-87021-929-4.
March, Edgar J. (1966). British Destroyers: A History of Development, 1892-1953; Drawn by Admiralty Permission From Official Records & Returns, Ships' Covers & Building Plans. London: Seeley Service. OCLC 164893555.
Smith, Peter C (2010). Fighting Flotilla: RN Laforey Class Destroyers in WW2. Barnsley, South Yorkshire: Pen & Sword Books. ISBN 978-1-84884-273-1.
Cernuschi, Enrico C (2010). Acque di Pantelleria, 15 giugno 1942. Parma: Albertelli editions.

External links

Wikimedia Commons has media related to QF 4.7 inch Mk XI naval gun.

QF Mark XI 4.7"/50 (12 cm) on Navweaps.com

British Commonwealth naval weapons of the Second World War

Monitor guns	BL 15 inch

Capital ship main armament	BL 14 inch BL 15 inch BL 16 inch

Heavy cruiser main armament	BL 7.5 inch Mk VI BL 8 inch Mk VIII

Secondary armament and light cruiser main armament	QF 4 inch Mk V QF 4.5 inch QF 5.25 inch BL 6 inch Mk XII BL 6 inch Mk XXII BL 6 inch Mk XXIII

Minesweeper, Sloop, Corvette, Frigate and Destroyer armament	QF 6 pounder 10 cwt QF 12 pdr 12 cwt Mk V QF 4 inch Mk IV BL 4 inch Mk IX QF 4 inch Mk XVI QF 4 inch Mk XIX QF 4.5 inch BL 4.7 inch Mk II QF 4.7 inch Mk IX & XII QF 4.7 inch Mk XI

Submarine guns	QF 12 pdr 12 cwt Mk V QF 3 inch 20 cwt QF 4 inch Mk XII & XXII

Anti-aircraft weapons	Unrotated Projectile Holman Projector 20 mm Oerlikon QF 2 pounder "pom-pom" Mk VIII 40 mm Bofors QF 3 inch 20 cwt QF 4 inch Mk V QF 4 inch Mk XVI QF 4.5 inch QF 4.7 inch Mk VIII

Light weapons	.303 Lewis machine gun .50 Vickers Mk III machine gun QF 3 pounder Vickers

Torpedoes	21 inch Mk VII 21 inch Mk VIII 21 inch Mk X 21 inch Mk XI 24.5 inch Mk I

Anti-submarine weapons	Thornycroft depth charge thrower Hedgehog Squid

Small craft armament	Molins 6 pounder Vickers K machine gun 18 inch torpedo

Foreign-sourced weapons	20 mm Oerlikon 40 mm Bofors 3-inch 23 caliber gun (US) 3-inch 50 caliber gun (US) 4-inch 50 caliber Mark 9 gun (US) 5-inch 51 caliber Mark 8 gun (US) Y-gun depth charge projector (US) Mark 8 torpedo (US)

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