QF 12-pounder 18 cwt naval gun

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Naval gun, Coastal defence

Ordnance QF 12-pounder 18 cwt
Deployed as anti-aircraft gun on HMS Agamemnon off Salonika, 1916
Type	Naval gun, Coastal defence
Place of origin	United Kingdom
Service history
In service	1906–1921?
Used by	Royal Navy
Wars	World War I
Production history
Designer	Elswick Ordnance Company
Designed	189?
Specifications
Mass	Gun & breech: 2,016 lb (914 kg)
Barrel length	Bore: 150-inch (3.81 m) (50 calibres)

Shell	Separate QF 12.5 lb (5.66 kg)
Calibre	3 in (76 mm)
Rate of fire	20 rd/min
Muzzle velocity	2,600 ft/s (790 m/s)
Effective firing range	9,300 yards @ +20° (8,500 m @ +20°)

The QF 12 pounder 18 cwt gun (Quick-Firing) was a 3-inch high-velocity naval gun used to equip larger British warships such as battleships for defence against torpedo boats. 18 cwt referred to the weight of gun and breech (18 × 112 lb = 2,016 lb or 914 kg), to differentiate the gun from others that also fired the "12 pound" (actually 12.5 lb or 5.7 kg) shell.

Service

Royal Navy service

Two guns mounted on roof of "X" turret, HMS *Dreadnought*

Guns were mounted in:

HMS Dreadnought commissioned 1906
The last three King Edward VII-class battleships—HMS Britannia, HMS Africa, and HMS Hibernia, commissioned 1906–1907
Lord Nelson-class battleships commissioned 1908
Minotaur-class armoured cruisers commissioned 1908–1909

The gun was superseded in the anti-torpedo boat role on new capital ships from 1909 onwards by the far more powerful BL 4-inch Mk VII gun.

World War I land service

In World War I four guns were landed for service in the East Africa campaign, on 10 February 1916, and were used until September. They constituted the 9th Field Battery manned by Royal Marines. They were originally towed by oxen and later by Napier lorries.

Fourteen of these guns were mounted in coast defence batteries in the 'Middle Line' of the defences of the Firth of Forth when it was established in 1915 (the batteries on Inchcolm (8 guns), Inchmickery (4) and Cramond Island (2). During the general revision of the defences in 1916/17 two of the guns were removed to store, four moved to other batteries (Hound Point and Downing Point). The document setting out the armaments of the Forth differentiate clearly between the 12cwt and 18cwt types, both of which were in use in the fortress.

Ammunition

The gun fired the same 12.5 lb 3-inch (76 mm) shells as the other British "QF 12 pounder" guns, but used its own larger separate cartridge case to accommodate a larger quantity of cordite propellant.


2 lb 12 oz (1.25 kg) cordite Cartridge Mk II, 1914	Mk II common pointed shell	Mk II & Mk III Common Lyddite shell	Mk IV Common Lyddite shell with internal night tracer, 1914	Mk IX Shrapnel shell, 1918

Notes

20 rounds per minute is quoted in Elswick gun tables of 1901, and may be considered optimistic
2600 ft/s: Range Tables for His Majesty's Fleet, 1910 February 1911 with 2 lb 12 oz (1.25 kg) cordite MD propellant. The gun first appears in Elswick gun Tables as quoted in Brasseys Naval Annual 1901 with a maximum muzzle velocity 2800 ft/s with "battering" charge of 3 lb cordite (Mk I), but this is not the charge adopted for British service.
The Sight Manual 1916
Farndale 1988, pages 316, 391. Farndale, quoting from the Official History, states they were from HMS Pegasus, but it did not carry these guns.
'History of Forth Defences from 1914 to November 1918' Fort Record Book, Inchcolm Fire Command, The National Archives, Kew, reference WO 192/108.

References

General Sir Martin Farndale, History of the Royal Regiment of Artillery. The Forgotten Fronts and the Home Base, 1914–18. London: The Royal Artillery Institution, 1988.
Tony DiGiulian, British 12-pdr (3"/50 (7.62 cm)) 18cwt QF Mark I

External links

v t e British Empire naval weapons of the First World War
Monitor guns	BL 9.2-inch Mk VI BL 9.2-inch Mk VIII BL 9.2-inch Mk X BL 9.2-inch Mk XII BL 12-inch Mk VIII BL 14-inch Mk II (US built) BL 15-inch Mk I BL 18-inch Mk I
Capital ship main armament	Vickers 10-inch 45 cal. EOC 10-inch 45 cal. BL 12-inch Mk VIII BL 12-inch Mk IX BL 12-inch Mk X BL 12-inch Mk XI & XII EOC 12-inch 45 cal. Mk XIII BL 13.5-inch Mk I – IV BL 13.5-inch Mk V BL 13.5-inch Mk VI EOC 14-inch 45 cal. Mk I BL 15-inch Mk I
Armoured cruiser main armament	BL 7.5-inch Mk I BL 9.2-inch Mk X BL 9.2-inch Mk XI
Secondary armament and light cruiser main armament	QF 12-pounder 18 cwt QF 14-pounder Maxim-Nordenfelt QF 14-pounder Mk I & II QF 4-inch Mk III BL 4-inch Mk VII QF 4-inch Mk V BL 4-inch Mk IX BL 5.5-inch Mk I QF 6-inch Mk I – III BL 6-inch Mk VII BL 6-inch Mk XI BL 6-inch Mk XII BL 6-inch Mk XIII-XVIII BL 7.5-inch Mk II – Mk V
Destroyer and small cruiser armament	QF 12-pounder 12 cwt Mk II QF 4-inch Mk III BL 4-inch Mk VIII QF 4-inch Mk IV BL 4.7-inch Mk I
Merchant ship armament	QF 4.7-inch Mk I – IV QF 4.7-inch Mk V*
Submarine guns	BL 4-inch Mk XI QF 4-inch Mk XII
Anti-aircraft guns	QF 2-pounder "pom-pom" Mk II QF 3-inch 20 cwt QF 4-inch Mk V
Light weapons	.303 Vickers machine gun QF 3-pounder Hotchkiss QF 3-pounder Vickers QF 6-pounder Hotchkiss
Torpedoes	18-inch Mk V – VIII 21-inch Mk II 21-inch Mk IV
Mines	Spherical Mk I, II and III Vickers Elia mine Type H mine
Anti-submarine weapons	Type A Depth charge Type B Depth charge Type C Depth charge Type D Depth charge Type E Depth charge Type F Depth charge Type G Depth charge Cruiser Mine 7.5-inch howitzer
Landing guns	QF 12-pounder 8 cwt

v t e British Empire artillery of the First World War
Armoured vehicle guns	QF 3-pounder Vickers QF 6-pounder Hotchkiss QF 6-pounder 6 cwt
Infantry guns	1.59-inch breech-loading Vickers Q.F. gun, Mk II
Field artillery	BL 12-pounder 6 cwt QF 12-pounder 8 cwt QF 12-pounder 18 cwt QF 13-pounder BL 15-pounder BLC 15-pounder QF 15-pounder QF 18-pounder QF 4-inch gun Mk III BL 4-inch gun Mk VII QF 4.5-inch howitzer
Medium & heavy artillery	QF 4.7-inch gun BL 5-inch howitzer BL 5.4-inch howitzer BL 60-pounder gun BLC 6-inch siege gun BL 6-inch gun Mk VII BL 6-inch gun Mk XIX BL 6-inch 26 cwt howitzer BL 6-inch 30 cwt howitzer BL 8-inch howitzer Mk I – V BL 8-inch howitzer Mk VI – VIII
Siege artillery	BL 7.5-inch Mk III naval gun BL 9.2-inch howitzer BL 9.2-inch Mk X naval gun BL 12-inch howitzer BL 12-inch Mk X naval gun BL 15-inch howitzer
Mountain artillery	RML 2.5-inch mountain gun BL 10-pounder mountain gun BL 2.75-inch mountain gun QF 2.95-inch mountain gun QF 3.7-inch mountain howitzer
Mortars	Garland trench mortar 3-inch Stokes mortar Vickers 1.57-inch mortar 2-inch medium mortar Newton 6-inch mortar 9.45-inch Heavy Mortar
Smoke and chemical weapons	4-inch Stokes Mortar Livens Projector Livens Large Gallery Flame Projector
Anti-aircraft guns	QF 1-pounder pom-pom QF 2-pounder "pom-pom" Mk II 75 mm AA gun QF 12-pounder 12 cwt QF 13-pounder 6 cwt QF 13-pounder Mk IV QF 13-pounder 9 cwt QF 3-inch 20 cwt QF 18-pounder QF 4-inch Mk V
Coastal artillery	QF 12-pounder 12 cwt QF 4-inch naval gun Mk I – III BL 6-inch Mk VII naval gun BL 9.2-inch Mk IX – X naval gun RML 9-inch
Railway guns	BL 9.2-inch railway gun BL 12-inch railway gun BL 12-inch railway howitzer BL 14-inch railway gun

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