|BL 6 inch gun Mk XII|
Casemate gun on HMS Warspite after the Battle of Jutland, June 1916
|Place of origin||United Kingdom|
|Used by||British Empire|
|Weight||15,512 pounds (7,036 kg) barrel & breech|
|Barrel length||270 inches (6.858 m) bore (45 cal)|
|Shell||100 pounds (45.36 kg) Lyddite, Armour-piercing, Shrapnel|
|Calibre||6 inches (152.4 mm)|
|Breech||Welin interrupted screw|
|Recoil||Hydro-spring, 16.5 inches (420 mm)|
|Rate of fire||5-7 rpm|
|Muzzle velocity||2,825 feet per second (861 m/s)|
|Maximum firing range||19,660 metres (21,500 yd)|
The BL 6 inch Gun Mark XII was a British 45 calibres naval gun which was mounted as primary armament on light cruisers and secondary armament on dreadnought battleships commissioned in the period 1914 - 1926, and remained in service on many warships until the end of World War II.
It superseded the 45-calibres Mk VII gun and the longer 50-calibres Mk XI gun which had proved unwieldy in light cruisers due to its length, and was Britain's most modern 6-inch naval gun when World War I began.
It was superseded as secondary armament on new battleships in the 1920s by the 50-calibre 6-inch Mk XXII gun, and as main armament on new light cruisers in the 1930s by the 50-calibre 6-inch Mk XXIII gun.
Guns were mounted in the following ships :
During WWII some Mk XII guns were used in emergency coast defense batteries.
This gun generated a higher pressure in the chamber on firing compared to preceding 6-inch guns such as Mk VII and Mk XI. This necessitated use of special shells capable of withstanding a pressure of 20 tons per square inch on firing, which had "Q" suffixed to the name. World War I shells were marked "A.Q." denoting special 4 C.R.H. shells for this gun.
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