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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
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7.5" (19 cm) turrets for HMS Shannon under
construction with 12-pdr 18cwt guns on top
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