BL 12 inch Mk XI – XII naval gun

BL 12 inch gun Mk XI, Mk XII
300px Aft Mk XI guns of HMS Vanguard
Type	Naval gun
Place of origin	United Kingdom
Service history
In service	1910 - 1920
Wars	World War I
Production history
Designer	Vickers
Manufacturer	Vickers
Specifications
Barrel length	600 inches (15.24 m) bore (50 cal)
Shell	850 pounds (385.6 kg) Lyddite, Armour-piercing, Shrapnel
Calibre	12 inches (304.8 mm)
Muzzle velocity	2,825 feet per second (861 m/s)
Maximum range	19,380 metres (21,190 yd)

The BL 12 inch Gun Mark XI and Mark XII were British 50-calibres naval guns that were mounted as primary armament on dreadnought battleships from 1910.

History

File:HMS Hercules 12 inch guns IWM Q 18062.jpg

Vice-Admiral Doveton Sturdee in front of the Mk XII guns of a wing turret on HMS Hercules

Mk XI had a longer (50 calibres, 600 inches) barrel than the previous Mk X gun (45 calibres), and was an attempt to increase the muzzle velocity, and hence armour-piercing capability and range, of a 12 inch gun. Problems such as bore erosion, which led to short barrel life, and poor accuracy due to inconsistent cordite propellant burning, meant the gun was not entirely satisfactory. The subsequent Mk XII gun suffered from the same problems.

Instead of attempting to improve the 12-inch gun, the British developed the 13.5-inch Mk V gun of 45-calibres, as it could achieve greater range at lower muzzle velocities due to its larger shell.

Mk XI guns were mounted in the following ships :

• St. Vincent class battleships laid down 1907, commissioned 1910
• HMS Neptune laid down 1909, commissioned 1911

Mk XII guns were mounted in the following ships :

• Colossus class battleships laid down 1909, commissioned 1911

See also

• 12px Media related to BL 12 inch Mk XI - XII naval gun at Wikimedia Commons
• Obukhovskii 12"/52 Pattern 1907 gun Russian equivalent
• 30.5 cm SK L/50 gun German equivalent
• List of naval guns

References

• Tony DiGiulian, British 12"/50 (30.5 cm) Marks XI, XI* and XII