4.7 inch QF Mark XII

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4.7 inch QF Mark XII

The 4.7 inch QF Mark XII was a destroyer weapon used by the Royal and Commonwealth Navies in WW2.[1] The CP Mk IX first appeared on the A-I class destroyers, on the CP Mk XIV single mounting. Starting with the Tribal class destroyers, it was fitted in the twin CP Mk XIX mounting with the twin gun then being renamed QF Mk XII. This mounting limited the maximum elevation to 40 degrees, but all CP Mk XIX mountings were equipped with Fuze Setting Pedestals or Mk V Fuze Setting Trays,[2] to allow the mountings to be fired against aircraft while being controlled by the Fuze Keeping Clock fire control computer. Typical maximum rate of fire was twelve rounds per gun, per minute.[3] The Mk XII gun fired a 50lb shell and used a separate cartridge, with both shell and cartridge being loaded via a loading tray, with power ramming, elevation, and traverse. The maximum range at 40 degrees elevation was 16,970 yards (15520m) fired at the new gun muzzle velocity of 2650fps (808m/s).[4] The 40 degree elevation was justified on the grounds that destroyers would be screening the battle-fleet during aerial attack, and 40 degrees elevation was adequate to engage aircraft that were concentrating their attack on other ships.[5]


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External links

Illustration of a 4.7 inch single mount
  1. Campbell, Naval Weapons of World War Two, p48.
  2. Hodges and Friedman, Destroyer weapons of WW2, P95-96.
  3. Hodges and Friedman, Destroyer weapons of WW2, p21.
  4. Campbell, Naval Weapons of World War Two, p48.
  5. Harding, editor, The Royal Navy, 1930-2000: innovation and defence, p19-41:, Pugh, Managing the aerial threat.