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BL 6-inch gun Mk VII
Field gun at full recoil after firing, Reningelst, Flanders, 15 June 1916. Colourised photograph on propaganda postcard
Type Naval gun
Coastal defence gun
Heavy field gun
Place of origin United Kingdom
Service history
In service 1901–72 (Fort Scratchley)
1915–18 (field use)
Wars World War I

World War II

Production history
Designer Vickers
Designed 1899
Number built 898
Variants Mk VII, Mk VIII, Mk XXIV
Weight 16,875 lb (7,654 kg) (gun & breech)
25 tons (gun on field carriage)
Barrel length 22 ft 4 in (6.81 m) (45 cal)

Shell Lyddite, HE, Shrapnel 100 lb (45 kg)[1]
Calibre 6 in (152 mm)
Breech Welin interrupted screw
Rate of fire 8 rpm[2]
Muzzle velocity 2,525 ft/s (770 m/s) (light charge)
2,775 ft/s (846 m/s) (heavy charge)[3]
Maximum range Field carriage Mk. II : 13,700 yd (12,500 m)[4] Naval : 14,600 yd (13,400 m) (light charge); 15,800 yd (14,400 m) (heavy charge)[5][6]
Filling weight Lyddite : 13 lb 5 oz (6.0 kg)
Amatol : 8 lb 14 oz (4.0 kg)
Shrapnel : 874 balls @ 27/lb[7]

The BL 6 inch Gun Mark VII (and the related Mk VIII)[8] was a British naval gun dating from 1899, which was mounted on a heavy traveling carriage in 1915 for British Army service to become one of the main heavy field guns in the First World War, and also served as one of the main coast defence guns throughout the British Empire until the 1950s.


The gun superseded the QF 6-inch gun of the 1890s, a period during which the Royal Navy had evaluated QF technology (i.e. loading propellant charges in brass cartridge cases) for all classes of guns up to 6 inch to increase rates of fire. BL Mk VII returned to loading charges in silk bags after it was determined that with new single-action breech mechanisms a 6-inch BL gun could be loaded, vent tube inserted and fired as quickly as a QF 6 inch gun. Cordite charges in silk bags stored for a BL gun were also considered to represent a considerable saving in weight and magazine space compared to the bulky brass QF cartridge cases.[9]

Naval gun

Forward starboard casemate guns on HMS Kent showing shell damage sustained in the Battle of the Falkland Islands

Gun drill on troop ship RMS Laconia in March 1942 (World War II)

The gun was introduced on the Formidable-class battleships of 1898 (commissioned September 1901) and went on to equip many capital ships, cruisers, monitors, and smaller ships such as the Insect-class gunboat which served throughout World War II.[5]

Mk VIII in Naval service was identical to Mk VII, except that the breech opened to the left instead of to the right, for use as the left gun in twin turrets.

Guns were mounted in the following ships :

In World War II the gun was used to arm British troop ships and Armed Merchant Cruisers, including HMS Rawalpindi, which briefly fought the German 11-inch gun battlecruisers Scharnhorst and Gneisenau in November 1939, and HMS Jervis Bay which similarly sacrificed herself to save her convoy from the 11-inch cruiser Admiral Scheer in November 1940 .

World War I field gun