BL 6 inch Mk XXIII naval gun

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Ordnance BL 6 inch gun Mk XXIII
HMS Belfast 3 db.jpg
Forward triple-gun turrets of HMS Belfast, March 2005
Type Naval gun
Place of origin United Kingdom
Service history
In service 1931 - 1985
Used by  Royal Navy
 Royal Australian Navy
 Royal New Zealand Navy
 Royal Canadian Navy
 Indian Navy
 Peruvian Navy
 Republic of China Navy
 People's Liberation Army Navy
Wars Second World War
Korean War
Production history
Number built 469[1]
Specifications
Weight 7 tonnes[1]
Barrel length 300 inches (7.6 meters)[1]

Shell 112 pounds (51 kg)
Calibre 6-inch (152.4 mm)[1]
Muzzle velocity 2760 feet per second (840 m/s)[1]
Maximum firing range 25,480 yd (23,300 m) at 45 degrees elevation[1]

The 50 calibre BL 6 inch gun Mark XXIII[2] was the main battery gun used on the Royal Navy and British Commonwealth's conventional (non-anti-aircraft) light cruisers built from 1930 through the Second World War, and passed into service with several other navies when ships were disposed of after the end of the War.

Description[edit]

Handling cordite charges inside a Mk XXIII turret aboard HMS Jamaica, 1943
Breech with shell on loading tray of centre gun in a turret on HMS Belfast, 2006

It replaced the BL 8 inch Mk VIII naval gun used on earlier Washington Naval Treaty cruisers. These built-up guns consisted of a tube and 4.5 metre jacket with a hand-operated Welin breech block. Cloth bags contained 14 kg (30 pound) charges of cordite or flashless (NQFP) powder for a 51-kg (112-pound) projectile. Useful life expectancy was 1100 effective full charges (EFC) with standard cordite and 2200 EFC with NQFP per barrel.[1] The typical maximum rate of fire was eight rounds per gun, per minute.[3] The Mk XXIII turret design was improved through a "long trunk" ammunition hoist, which reduced the crew requirements and increased the speed of the ammunition hoists. As in the MK XXII turret loading could be accomplished at any angle up to 12.5 degrees gun elevation.[4] A RN gunnery officer on HMS Bermuda gave details of the loading cycle which could be attained in the Mk XXIII turret with a well trained crew: "...a loading cycle of four and a half to 5 seconds was attained at low elevation, another two to three seconds being required with the guns elevated for long range. The time would lengthen as fatigue set in, but was creditable..." [5]

Ships mounting BL 6 inch Mk XXIII guns[edit]

Ship Gun Installation[1]
HMNZS Achilles four 95-ton Mk XXI twin turrets
HMS Ajax four 95-ton Mk XXI twin turrets
HMS Arethusa three 95-ton Mk XXI twin turrets
HMS Aurora three 95-ton Mk XXI twin turrets
HMS Belfast four 175-ton Mk XXIII triple turrets
HMS Bermuda four 175-ton Mk XXIII triple turrets
HMS Birmingham four 150-ton Mk XXII triple turrets
HMS Ceylon three 175-ton Mk XXIII triple turrets
HMS Edinburgh four 175-ton Mk XXIII triple turrets
HMS Fiji four 175-ton Mk XXIII triple turrets
HMS Galatea three 95-ton Mk XXI twin turrets
HMS Gambia four 175-ton Mk XXIII triple turrets
HMS Glasgow four 150-ton Mk XXII triple turrets
HMS Gloucester four 150-ton Mk XXII triple turrets
HMAS Hobart four 95-ton Mk XXI twin turrets
HMS Jamaica four 175-ton Mk XXIII triple turrets
HMS Kenya four 175-ton Mk XXIII triple turrets
HMNZS Leander four 95-ton Mk XXI twin turrets
HMS Liverpool four 150-ton Mk XXII triple turrets
HMS Manchester four 150-ton Mk XXII triple turrets
HMS Mauritius four 175-ton Mk XXIII triple turrets
HMS Neptune four 95-ton Mk XXI twin turrets
HMS Newcastle four 150-ton Mk XXII triple turrets
HMS Newfoundland three 175-ton Mk XXIII triple turrets
HMS Nigeria four 175-ton Mk XXIII triple turrets
HMCS Ontario three 175-ton Mk XXIII triple turrets
HMS Orion four 95-ton Mk XXI twin turrets
HMS Penelope three 95-ton Mk XXI twin turrets
HMAS Perth four 95-ton Mk XXI twin turrets
HMS Sheffield four 150-ton Mk XXII triple turrets
HMS Southampton four 150-ton Mk XXII triple turrets
HMS Superb three 175-ton Mk XXIII triple turrets
HMS Swiftsure three 175-ton Mk XXIII triple turrets
HMAS Sydney four 95-ton Mk XXI twin turrets
HMS Uganda three 175-ton Mk XXIII triple turrets

Shell trajectory[edit]

Range[1] Elevation Time of flight Descent Impact velocity
5000 yd (4.6 km) 2° 23′ 7 sec 3° 0′ 1939 ft/s (591 m/s)
10000 yd (9.1 km) 6° 15′ 16 sec 9° 57′ 1371 ft/s (418 m/s)
15000 yd (14 km) 13° 6′ 29 sec 23° 38′ 1098 ft/s (335 m/s)
20000 yd (18 km) 24° 7′ 47 sec 39° 52′ 1087 ft/s (331 m/s)
24500 yd (22.4 km) 41° 4′ 71 sec 56° 27′ 1159 ft/s (353 m/s)

Ammunition[edit]

See also[edit]

Weapons of comparable role, performance and era[edit]

Surviving examples[edit]

  • Y turret from HMNZS Achilles (70), later INS Delhi (1948), is preserved at the entrance to Devonport Naval Base, Auckland, New Zealand.
  • A second turret from INS Delhi (1948), is preserved at the Indian Military Academy, Dehradun.
  • 12 guns and four turrets are preserved on the museum ship HMS Belfast (C35) in London, UK
  • A number of Mark XXIIIs can also be found at English Heritage or other sites historical sites being used to represent earlier marks which were used as coastal artillery. Tilbury Fort, Essex, has one barrel; Coalhouse Fort, East Tilbury, Essex has two barrels; Gravesend, Kent, has one barrel; the Tynemouth gun emplacement has one barrel.

Notes and references[edit]

  1. ^ a b c d e f g h i Campbell 1985 pp.34-36
  2. ^ Mark XXIII = Mark 23. Britain used Roman numerals to denote Marks (models) of ordnance until after World War II. Mark XXIII indicates this was the twenty-third model of BL 6-inch gun.
  3. ^ O.U. 6359A, Handbook for 6-Inch, B.L., Mark XXIII Guns on Triple, Mark XXII Mounting, 1937, page 8.
  4. ^ Campbell, Naval Weapons of WWII, p.35-36.
  5. ^ Brooke, p.200

Bibliography[edit]

  • Brooke,Geoffrey (1982). Alarm Starboard!. Cambridge: Stevens. ISBN 0850595789. 
  • Campbell, John (1985). Naval Weapons of World War Two. Naval Institute Press. ISBN 0-87021-459-4. 
  • Lenton, H.T. & Colledge, J.J (1968). British and Dominion Warships of World War Two. Doubleday and Company. 

External links[edit]