The Mark II** and Mark V were modified designs intended from the start as naval guns. Mark II** guns were made by Woolwich, Elswick and Vickers, with slight differences between the various manufacturers. Only Vickers made the Mark V gun. These naval guns were used as secondaries on the last British armored cruisers.
Extracts from Admiral E.C. Troubridge's court-martial (for letting Goeben get away in 1914) regarding these guns include this comment: "For the 9.2-inch Mark X and XI and 7.5-inch Mark II the average spread [dispersion] was 200 - 250 yards at a range of 7000 - 8000 yards."
Some additional details for these guns from the June 1914 battle practice for Defence and Warrior; no speeds or courses of the firing ship or target are given: At just under 8,000 yards (7,300 m), Defence scored 5 direct hits and 1 ricochet with her 9.2" (23.4 cm) guns and 8 hits and 1 ricochet from her 7.5" (19 cm) guns. Defence fired 29 rounds from her 9.2" (23.4 cm) guns and 62 rounds from her 7.5" (19 cm) guns in 6 minutes. Her director firing system broke down during the practice preventing more hits being made. At the same range, Warrior scored 7 hits and 5 ricochets from her 9.2" (23.4 cm) guns and 2 hits and 4 ricochets from her 7.5" (19 cm) guns. Warrior fired 40 rounds from her 9.2" (23.4 cm) guns and 19 rounds from her 7.5" (19 cm) guns in 4 minutes 15 seconds.
In late June 1918 six guns were offered to the Army for relining to high-velocity AAA weapons, but this offer was declined.
Mark II was constructed of A tube, breech ring screwed to the jacket and a "pure couple" breech mechanism. Mark II* differed only in a thicker 'A' tube over the breech bush, the Mark II** was a navalized version. There were different versions of the Mark II**, as two guns were to a Woolwich design, eight to a slightly different Elswick design and six to a Vickers design. Mainly, the Mark II** differed from the Mark II* in that it had generally thicker A tube with correspondingly less wire, a thicker inner A tube in some units and the rear end of the jacket was reinforced by a screwed or shrunk on C hoop immediately in front of the breech ring. The Mark V was like the Mark II** but there was no 'C' hoop. "Steel choke" was a problem and many guns had cannelured rings as a corrective measure.
Of the naval guns, besides the five transferred Mark II guns, 16 Mark II** and 40 Mark V were manufactured. By 1939, a total of 25 of these guns remained, four Mark II, one Mark II** and 20 Mark V. These had been retained for possible use in monitors, but the mountings had been scrapped in 1938-39, making it impossible to use the guns. For that reason, most of these guns were scrapped in 1943-44, although four were retained for experimental purposes.
Two guns were made for Canada prior to World War I and were known as Vickers Mark C. These guns only differed in rifling details from the Mark V.
HMS Minotaur prior to World War I
7.5" (19 cm) turrets for HMS Shannon under
construction with 12-pdr 18cwt guns on top
|Designation||7.5"/50 (19 cm) Mark II
7.5"/50 (19 cm) Mark V
|Ship Class Used On||Warrior, Minotaur and Achilles classes|
|Date Of Design||about 1905|
|Date In Service||1908|
|Gun Weight||Mark II: 14.56 tons (14.8 mt)
Mark V: 15.06 tons (15.3 mt)
|Gun Length oa||386.7 in (9.822 m)|
|Bore Length||about 375.0 in (9.525 m)|
|Rate Of Fire||5 - 6 rounds per minute|
|Note: Danger space for
this gun against a 30 foot (9.1 m) target was estimated as follows:
75 yards at 8,000 yards (69 m at 7,300 m)
30 yards at 12,000 yards (27 m at 10,970 m)
0 yards at 16,000 yards ( 0 m at 14,630 m)
|Projectile Types and Weights||AP - 200 lbs. (90.7 kg)
Common - 200 lbs. (90.7 kg)
CPC - 200 lbs. (90.7 kg)
HE - 200 lbs. (90.7 kg)
|Muzzle Velocity||2,827 fps (862 mps)|
|Approximate Barrel Life||650 rounds|
|Ammunition stowage per gun||100 rounds|
|Note: Shells were mainly 2crh, but 4crh was later issued to the Minotaur class.|
|Elevation||With 200 lbs. (90.7) CPC Shell|
|Range @ 15 degrees with 2crh||14,328 yards (13,100 m)|
|Range @ 15 degrees with 4crh||15,571 yards (14,240 m)|
|Note: Taken from range tables, but "British Naval Guns 1880-1945 No 9" says that the 2crh figures were probably about 200 yards (180 m) too long.|
|Range||KC Side Armor|
|3,000 yards (2,740 m)||4.5 in (11.4 cm)|
|Note: Data from "The Grand Fleet: Warship Design and Development 1906-1922" for an angle of obliquity of 30 degrees and a striking velocity of 1,683 fps (513 mps). Projectiles were salt-filled (blind).|
Warrior (4), Minotaur (10) and Achilles (4): CP Mark III
|Elevation||about -5 / +15 degrees|
|Elevation Rate||Manual operation, only|
|Train||about +150 / -150 degrees|
28 December 2008 - Benchmark
18 February 2009 - Added additonal construction details