BL 8-inch Mk VIII naval gun

Ordnance BL 8 inch gun Mk VIII
Forward 8-inch turrets aboard HMAS Canberra
Type	Naval gun Coast defence gun
Place of origin	United Kingdom
Service history
In service	1927 – 1954[1]
Used by	Royal Navy Royal Australian Navy Spanish Navy
Wars	Second World War Spanish Civil War
Production history
No. built	168[2]
Specifications
Mass	17.5 tonnes[2]
Barrel length	400 inches/10 meters(50 calibres)[2]
Shell	256 pounds (116 kg)
Calibre	8-inch (203 mm)[2]
Muzzle velocity	2805 feet per second (855 m/s)[2]
Maximum firing range	28 kilometres (17 mi)[2]

The BL 8 inch gun Mark VIII^{[note 1]} was the main battery gun used on the Royal Navy's County-class cruisers,^{[note 2]} in compliance with the Washington Naval Treaty of 1922. This treaty allowed ships of not more than 10,000 tons standard displacement and with guns no larger than 8 inches (203 mm) to be excluded from total tonnage limitations on a nation's capital ships. The 10,000 ton limit was a major factor in design decisions such as turrets and gun mountings. A similar gun formed the main battery of Spanish Canarias-class cruisers.^[3] In 1930, the Royal Navy adopted the BL 6 inch Mk XXIII naval gun as the standard cruiser main battery in preference to this 8-inch gun.^[4]

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