BL 12 inch Mk XI – XII gun

• Is Artillery — yes • Is Explosive — yes • Is Uk — yes • Is Ranged — yes • Name — BL 12-inch Mk XI and Mk XII gun • Origin — United Kingdom • Wars — World War I • Type — Naval gun • Designer — Vickers • Manufacturer — Vickers Armstrong Whitworth Coventry Ordnance Works William Beardmore and Company • Service — 1910–1922 • Caliber — 12 in • Part Length — 50 ft bore (50 calibers) • Velocity — 2825 ft/s • Cartridge — 850 lb Lyddite, Armour-piercing, Shrapnel • Max Range — 19380 m • Weight — 147,000 to 151,648 lbs (65.625 to 67.7 long tons or 65.7 to 68.8 tonnes)

• Illustration — Vice-Admiral Doveton Sturdee in front of the Mk XII guns of a wing turret on HMS Hercules In an effort to increase the armour-piercing capability and range of a 12-inch gun, the 50 calibres/600 inches Mk XI's barrel was 5 calibres/60 inches longer than the previous Mk X gun's 45 calibres. As a result, muzzle velocity increased from 2700 ft/s to 2825 ft/s, but bore erosion, which led to short barrel life, and poor accuracy due to inconsistent cordite propellant burning, hampered the gun. The Mk XII derived from it suffered from the same problems. Instead of attempting to improve their 12-inch gun, the British developed the 13.5-inch Mk V gun of 45-calibres, which could achieve greater range at lower muzzle velocities due to its larger shell. Mk XI guns were mounted on: • St. Vincent-class battleships laid down 1907, commissioned 1910 • HMS Neptune laid down 1909, commissioned 1911 Mk XII guns were mounted on: • Colossus-class battleships laid down 1909, commissioned 1911

• Obukhovskii 12"/52 Pattern 1907 gun Russian equivalent • 30.5 cm SK L/50 gun German equivalent • Škoda 30.5 cm /45 K10 Austro-Hungarian equivalent

BL 12 inch Mk XI – XII gun is associated with United Kingdom of Great Britain and Ireland. Classified as a rifled breech loader or naval artillery.