Of built-up construction and wire wound, generally similar to the Mark 12. Used a hand-worked Welin breech-block and an Elswick sliding hinge mechanism, with the fore portion of the breech being conical. A total of 29 guns were made.
The Mark XXI was originally ordered by Chile as a coastal defense gun and was almost identical to the Mark XVII except for a longer chamber, B tube and jacket rather than a full length jacket. Sixteen guns were made of which ten were taken over by the British Army for coast defense.
The data that follows is for the Mark XVII except where specified.
6"/50 (15.2 cm) gun from Chilean battleship
Latorre now at Museo de Cañones Navales in Bahia de Valparaíso,
|Designation||6"/50 (15.2 cm) BL Mark XVII
6"/50 (15.2 cm) BL Mark XXI
|Ship Class Used On||Mark XVII: Canada and Eagle
Mark XXI: Coast defense batteries
|Date Of Design||1913|
|Date In Service||1914|
|Gun Weight||19,524 lbs. (8,856 kg)|
|Gun Length oa||310.4 in (7.885 m)|
|Bore Length||300.0 in (7.620 m)|
|Chamber Volume||1,650 in3 (27.04 dm3)|
|Rate Of Fire
|5 - 7 rounds per minute|
|Note: The Rate of Fire
figure given above is found in references for British guns of this caliber,
but "Warrior to Dreadnought: Warship Development 1860-1905" quotes
Jellicoe's 1906 figures for rates of fire for these guns in gunlayers'
tests and in battle practice and notes that the latter figures corresponded
well to those actually attained by the Japanese at Tsushima:
Gunlayers Test: 12 rounds
In "Jutland: An Analysis of the Fighting" by John Campbell, it is stated that Canada's hoists were capable of supplying about 5.5 rounds per minute, a more rapid figure than her RN contemporaries.
|Projectile Types and Weights||CPC 4crh - 100 lbs. (45.3 kg)
HE 4crh - 100 lbs. (45.3 kg)
|Bursting Charge||CPC - 7.5 lbs. (3.4 kg)
HE - 13.3 lbs. (6.0 kg)
|Projectile Length||CPC - 23.5 in (59.7 cm)
HE - 22.9 in (58.2 cm)
|Propellant Charge||28.6 lbs. (13.0 kg) MD26
28.1 lbs. (12.76 kg) SC140
|Muzzle Velocity||2,905 fps (885 mps)|
|Approximate Barrel Life||N/A|
|Ammunition stowage per gun||200 rounds|
|Elevation||With 100 lbs. (45.36) CPC Shell|
|Range @ 20 degrees||16,190 yards (14,800 m)|
Canada (16): PXII
Eagle (9): PXII*
|Weight||30,520 lbs. (13,844 kg) without shield|
|Elevation||PXII: -7 / +15 degrees
PXII*: -7 / +20 degrees
|Elevation Rate||Manual operation, only|
|Train||about +80 / -80 degrees|
|Train Rate||Manual operation, only|
1) HMS Canada had her two after guns removed in 1916 after it was found that blast from the 14-inch "Q" turret caused problems.
2) The shields for these guns were of a new Vickers design which allowed full elevation and depression over all arcs of fire.
05 April 2008 - Benchmark
11 February 2012 - Updated to latest template
04 February 2014 - Added ammunition stowage and mounting note about gun shields.
15 March 2016 - Corrected sinking of HMS Eagle, miscellaneous additions