Bl 8-Inch Mk Viii Naval Gun

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. 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.

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
Used by	Royal Navy Royal Australian Navy Spanish Navy
Wars	Second World War Spanish Civil War
Production history
No. built	168
Specifications
Mass	17.5 tonnes
Barrel length	400 inches/10 meters(50 calibres)
Shell	256 pounds (116 kg)
Calibre	8-inch (203 mm)
Muzzle velocity	2805 feet per second (855 m/s)
Maximum firing range	28 kilometres (17 mi)

These guns, 50 calibres long, were built-up guns which consisted of a wire-wound tube encased within a second tube and jacket with a Welin breech block and hydraulic or hand-operated Asbury mechanism. Two cloth bags each containing 15 kg (33 lb) of cordite were used to fire a 116 kg (256 lb) projectile. Mark I turrets allowed gun elevation to 70 degrees to fire high-explosive shells against aircraft. Hydraulic pumps proved incapable of providing sufficient train and elevation speed to follow contemporary aircraft; so simplified version of the Mark II turrets with a maximum elevation of 50 degrees were installed in Exeter. Each gun could fire approximately five rounds per minute. Useful life expectancy was 550 effective full charges (EFC) per barrel.

The following ships mounted Mk VIII guns in 188-tonne twin turrets. The standard main battery was four turrets, but Exeter and York carried only three to reduce weight and formed the separate York class.

• County-class heavy cruisers : 13 ships
  • Canarias-class heavy cruisers : 2 ships
• York-class heavy cruisers : 2 ships

 

Six single guns capable of elevating to 70 degrees were installed as coastal artillery in the Folkestone-Dover area during the Second World War.

•  
  World War II semi-armour-piercing shell with marker dye to identify ship that fired it for range corrections
•  
  1930s high-explosive shell
•  
  Coast-defence gun shells, World War II

Range with 256 lbs. (116.1) SAPC with MV = 2,725 fps (831 mps)

Weapons of comparable role, performance and era

• 203mm/50 Modèle 1924 gun French equivalent
• 20.3 cm SK C/34 Naval gun German equivalent
• 203 mm /53 Italian naval gun Italian equivalent
• 20 cm/50 3rd Year Type naval gun Japanese equivalent
• 8"/55 caliber gun US equivalent

• A gun from HMAS Australia outside the Australian War Memorial, Canberra