BL 14 inch Mk VII naval gun

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BL 14 inch Mark VII
HMS Duke of York gunners A 021168.jpg
Gunners and forward turrets of HMS Duke of York after the Battle of North Cape
Type Naval gun
Place of origin UK
Service history
In service 1940-1945
Used by UK
Production history
Designed 1937
No. built 78
Weight 80.26 metric tons (176,900 lb)
Barrel length 53 ft 6 in (16.31 m) bore (45 calibres)

Shell 1,590 lb (720 kg)
Calibre 14 inches (355.6 mm)
Elevation Naval: 41°
Coastal: 45°
Rate of fire 2 rounds per minute
Muzzle velocity Standard Charge: 2,483 ft/s (757 m/s) (new gun), 2,400 ft/s (730 m/s) (25% wear)[1]
Maximum firing range 38,600 yd (35,300 m) at 40° with new linings, or 36,500 yd (33,400 m) at 40.7° (25% wear)

The BL 14 inch Mk VII naval gun[2] was a breech loading (BL) gun designed for the battleships of the Royal Navy in the late 1930s. This gun armed the King George V-class battleships during the Second World War.


The choice of calibre was limited by the Second London Naval Treaty, an extension of the Washington Naval Treaty which set limits on the size armament and number of battleships constructed by the major powers. After disappointing experiences with the combination of high velocity but relatively light shell in the BL 16 inch /45 naval gun of the Nelson-class battleships, the British reverted to the combination of lower velocities and (relatively) heavier shells in this weapon.[3]


The built-up gun was of an all-steel construction, using a radial expansion design; this was an advance on earlier British heavy guns, which employed a wire-wound technology. The resulting gun was lighter, less prone to droop, more accurate and had a significantly longer barrel life. The estimated barrel life was 340 effective full charges. The new 14-inch Armour Piercing (AP) 1,590-pound shell had, relative to its size, superior ballistic performance and armour-penetration compared to previous British shells, due to improvements in design and material which had taken place since World War I.[4] The shell also carried a very large[5][6] bursting charge of 48.5 lb (22.0 kg)[7]

The choice of mounting was a mechanically complex, quadruple turret (each battleship had 2 quadruple turrets (Mark III) and one twin turret (Mark II)). The turret and ammunition-handling facilities incorporated many anti-flash measures and interlocks, improving safety but adding to complexity.[8]


On entering operational service the turrets gained an initial reputation for unreliability, with individual guns and entire turrets jamming in action. However, it has been argued that these jams were typically caused by errors in drill, either due to lack of gun crew training, as was the case when the newly commissioned HMS Prince of Wales engaged the Bismarck in the Battle of the Denmark Strait (1941), or due to crew fatigue resulting from the prolonged nature of the engagement, as was the case when HMS King George V engaged Bismarck in 1941 and HMS Duke of York engaged Scharnhorst in the Battle of North Cape (1943).[9] In the latter battle Duke of York fired 52 broadsides, of these 31 straddled the target and a further 16 fell within 200 yards - an excellent performance, even when radar-control is taken into account.[10] The effects of the 14-inch shellfire on Scharnhorst were notable: Duke of York's first salvo put 'A' turret out of action, 'B' turret soon followed, a subsequent hit penetrated the German ship's armour, detonating in one of the boiler rooms and reducing the vessel's speed. This reduction in speed meant that the Scharhorst could not escape pursuit, and was responsible for her eventual destruction.[11]

By being instrumental in the destruction of two modern enemy battleships, the 14-inch Mark VII gun was, arguably, the most successful battleship main armament of World War II.[12]

Coastal guns[edit]

"Pooh" in March 1941
"Winnie", a 14-inch gun at St Margaret's at Cliffe near Dover, March 1941

Two guns, nicknamed Winnie and Pooh, were also mounted in World War II as coastal artillery near Dover to engage German batteries across the Channel in occupied France.

Armour penetration[edit]

  • Penetration at a muzzle velocity of 2483 ft/s, guns with new linings or with no significant wear:
  • Belt
    • 729 mm (28.7 in) @ 0 m (0yd)
    • 531 mm (20.9 in) @ 9,144 m (10,000 yd)
    • 452 mm (17.8 in) @ 13,716 m (15,000 yd)
    • 389 mm (15.3 in) @ 18,288 m (20,000 yd)
  • Decks
    • 33 mm (1.3 in) @ 9,144 m (10,000 yd)
    • 51 mm (2.0 in) @ 13,716 m (15,000 yd)
    • 69 mm (2.7 in) @ 18,288 m (20,000 yd)
    • 89 mm (3.5 in) @ 22,860 m (25,000 yd)
    • 107 mm (4.2 in) @ 25,603 m (28,000 yd)

Surviving example[edit]

See also[edit]


  1. ^ With 338.3 lb (153.5 kg) cordite.
  2. ^ Mk VII = Mark 7. Britain used Roman numerals to denote Marks (models) of ordnance until after World War II. This was the seventh model of BL 14-inch naval gun.
  3. ^ Raven and Roberts, p. 283
  4. ^ Raven and Roberts, p. 285
  5. ^ Naval Weapons index, The German KM 38 cm/52 SK C/34 (15-inch) carried a 41.4lb bursting charge, while the USN 16-inch Mk VI 2700 lb AP shell carried a 40.9lb bursting charge
  6. ^ USN Bureau of Ordnance, Naval Ordnance 1937 Edition, paragraph 1318: "The impact damage which a projectile itself does is entirely secondary to that which results from its burst. The design of most naval projectiles is based primarily on using the projectile as a vehicle with which to carry a quantity of explosive into a ship and secondarily to provide missiles with which to carry the force of the explosion."
  7. ^ Tony DiGiulian. "British 14"/45 (35.6 cm) Mark VII". NavWeaps. 
  8. ^ Kaplan, p. 88
  9. ^ Kaplan, p. 88
  10. ^ Burt, p. 390
  11. ^ Raven and Roberts, p. 356
  12. ^ Other battleship main armaments largely responsible for destroying battleships in WWII: the German 38 cm SK C/34 naval gun (15-inch) sank 1 battleship, HMS Hood; a combination of the American 16"/45 caliber gun and the 14"/50 caliber gun sank 1 battleship, Yamashiro; and the American 16"/45 caliber Mark 6 gun destroyed 1 battleship, Kirishima, the British BL 16 inch Mk I naval gun (combined with the BL 14 inch Mk VII naval gun) destroyed 1 battleship, the Bismarck. It is notable that the only modern battleships destroyed by battleship gunfire were the Bismarck and Scharnhorst, all the other battleships to suffer this fate were designs dating back to WWI, with various degrees of modernisation.


External links[edit]