BL 6 inch Mk XXIII naval gun
The 50 calibre BL 6 inch gun Mark XXIII[note 1] 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
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.[2] 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.[3] 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..." [4]
Ships mounting BL 6 inch Mk XXIII guns
Shell trajectory
| 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
-
S.A.P. shells (left), cordite cartridge (lower right) and cartridge container (centre right) on HMS Belfast
See also
Weapons of comparable role, performance and era
Surviving examples
- 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
- ↑ 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.
References
Bibliography
- 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
Royal Navy
Royal Australian Navy
Royal New Zealand Navy
Royal Canadian Navy
Indian Navy.svg.png){kind=small}
Peruvian Navy
Republic of China Navy
People's Liberation Army Navy
