These guns were an Elswick design generally similar to the Mark XI and developed for the Brazilian battleship Rio de Janeiro. That ship was taken over by the British and renamed HMS Agincourt at the start of World War I. After she was scrapped, these guns were then reused in the gunboats HMS Aphis and HMS Ladybird in 1939. Some guns were used in emergency coast defense batteries during World War II.
Constructed of inner A tube, A tube and breech piece joined by a securing collar, wire, B tube, jacket, breech ring and breeech bush. Spare guns differed in having a B tube and jacket rather than a full-length jacket. Used a hand-worked Welin breech-block. A total of 24 guns were built.
| Designation | 6"/50 (15.2 cm) BL Mark XIII |
|---|---|
| Ship Class Used On | HMS Agincourt HMS Aphis and HMS Ladybird in 1939 |
| Date Of Design | 1912 |
| Date In Service | 1914 |
| Gun Weight | 19,660 lbs. (8,918 kg) |
| Gun Length oa | 310.4in (7.867 m) |
| Bore Length | 300.0 in (7.620 m) |
| Rifling Length | N/A |
| Grooves | N/A |
| Lands | N/A |
| Twist | N/A |
| Chamber Volume | 1,550 in3 (25.40 dm3) |
| Rate Of Fire | 5 - 7 rounds per minute 12 |
- ^
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 per minute Battle Practice 4 rounds per minute - ^In "Jutland: An Analysis of the Fighting" by John Campbell, it is stated that almost all British capital ships had few or slow hoists for their 6" (15.2 cm) guns and that once the ready ammunition was used up, the rate of fire dropped to about 3 rounds per minute.
| Type | Bag |
|---|---|
| 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 | 24.6 lbs. (11.2 kg) MD26 24.4 lbs. (11.1 kg) SC140 |
| Muzzle Velocity | 2,770 fps (844 mps) |
| Working Pressure | N/A |
| Approximate Barrel Life | N/A |
| Ammunition stowage per gun | about 150 rounds |
Data from:
- "Warrior to Dreadnought: Warship Development 1860-1905" by D.K. Brown
- "Naval Weapons of World War Two" and "British Naval Guns 1880-1945 No 12" article in "Warship Volume VIII" both by John Campbell
- "The Big Battleship" by Richard Hough
- "British Battleships: 1860 - 1950" by Oscar Parkes
- "A Concentrated Effort: Royal Navy Gunnery Exercises at the End of the Great War" article by William Schleihauf in "Warship International" No. 2, 1998
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