The Repulse class battlecruisers used both single and triple mountings, with the latter mounting having the guns individually sleeved, an unusual feature for a secondary weapon. This mounting required a very large crew of 32 and, as it lacked power assist, proved to be quite cumbersome.
During World War II, this weapon was used in single mountings on many corvettes as well as on numerous smaller ships including 1,200 on DEMS.
Mark IX was of wire wound construction with tapered inner A tube and jacket. Mark IX* differed in having no inner A tube. Mark IX** was introduced to suit older manufacturing equipment at EOC and COW and had no inner A tube, a B tube and overlapping short jacket and an old-style step wire-winding method. All had Welin breech blocks with Vickers mechanisms. Some 2,382 were built of which 2,193 were still in service as of September 1939. Actual bore length was 44.35 calibers.
The Mark X was originally built for the Norwegian Nidaros class coastal defense ships which were taken over at the start of World War I and became the HMS Glatton class. These guns were of Elswick Pattern T and were partly wire wound with coned breech block. A total of fifteen guns were built and these were used only on DAMS.
The data that follows is specifically for the Mark IX, but the ballistics for the Mark X were similar.
4"/45 (10.2 cm) gun on HMCS Sherbrooke
|Designation||4"/45 (10.2 cm) BL Mark IX and Mark X|
|Ship Class Used On||Mark IX
World War I
Renown and Courageous classes
Inflexible as rearmed
Erebus and Marshal Ney classes
Sir John Moore and M.27
World War II
|Date Of Design||About 1913|
|Date In Service||1916|
|Gun Weight||Without Breech Mechanism: 4,620
lbs. (2,096 kg)
With Breech Mechanism: 4,749 lbs. (2,154 kg)
|Gun Length oa||184.6 in (4.689 m)|
|Bore Length||177.4 in (4.506 m)|
|Rifling Length||149.4 in (3.795 m)|
|Grooves||(32) 0.037 in deep x 0.270 (0.94 x 6.86 mm)|
|Lands||0.1227 in (3.117 mm)|
|Twist||Uniform RH 1 in 30|
|Chamber Volume||470.3 in3 (7.707 dm3)|
|Rate Of Fire||10 - 12 rounds per minute|
|Projectile Types and Weights||HE - 31 lbs. (14.1 kg)
SAP - N/A [probably about 31 lbs. (14.1 kg)]
|Propellant Charge||World War I: 7.7 lbs. (3.5 kg) MD16
World War II: 7.9 lbs. (3.59 kg) SC103 or 9.39 lbs. (4.3 kg) NF/S164-048
|Muzzle Velocity||2,625 fps (800 mps)|
|Working Pressure||18.5 tons/in2 (2,910 kg/cm2)|
|Approximate Barrel Life||3,600 rounds|
|Ammunition stowage per gun
(see Notes 3 and 4)
|Inflexible: 150 rounds
Monitors: 400 rounds
1) SAP was 3crh.
2) Outfits included up to 100 star shells per ship.
3) Monitor outfit was 250 HE and 150 SAP per barrel plus 50 starshell per ship.
4) Inflexible outfit was 37 CP, 90 HE, 23 HE Night tracer.
|Range @ 30 degrees||13,500 yards (12,344 m)|
|Elevation||With 31 lbs. (14.1 kg) HE Shell|
|Range @ 30 degrees||13,840 yards (12,660 m)|
(see Note 2)
Renown (5), Courageous (6) and M27 (1): T.I. Mark I
|Weight||T.I. Mark I (less shield): 17.475
tons (17.755 mt)
T.I. Mark I (with shield): 18.5 tons (18.8 mt)
CPI: 4.721 tons (4.797 mt)
|Elevation||T.I. Mark I: -10 / +30 degrees
CPI: -10 / +30 degrees
|Elevation Rate||Manually operated, only|
|Train Rate||Manually operated, only|
1) As mentioned above, the triple mount was a clumsy design. Quoting from "The Loss of Repulse and Prince of Wales" by A.E. Jacobs: "The triple mountings were always extremely difficult to train, and the general procedure when moving through a large arc was for the two trainers at the 'normal' and 'director' training wheels to be assisted by the remainder of the crew pushing on the breeches or muzzles."
2) The Monitors had many armament changes during their careers. The quantities shown above represent the maximum number of guns carried at any time.
19 July 2006 - Benchmark
28 February 2009 - Added information about monitors
03 January 2010 - Added photograph of Sherbrooke
25 January 2010 - Created additional pictures Page
19 May 2012 - Added reference
03 February 2014 - Added ammunition outfit and mounting information for Inflexible