QF 4-inch naval gun Mk IV, XII, XXII

The QF 4-inch gun Mk IV[note 1] was the main gun on most Royal Navy and British Empire destroyers in World War I. It was introduced in 1911 as a faster-loading light gun successor to the BL 4 inch Mk VIII gun. Of the 1,141 produced, 939 were still available in 1939.[1] Mk XII and Mk XXII variants armed many British interwar and World War II submarines.

Ordnance QF 4 inch gun Mk IV, XII, XXII
Mk IV gun from HMS Lance at the Imperial War Museum, London
TypeLight Naval gun
Submarine gun
Place of originUnited Kingdom
Service history
In service1911-1940s
Used byUnited Kingdom
WarsWorld War I
World War II
Production history
No. built1,141[1]
Mass2,750 pounds (1,250 kg) barrel & breech
Barrel length160 inches (4.064 m) bore (40 calibres)

ShellMk IV : Separate QF 31 pounds (14.06 kg);
Mk XII & XXII : Fixed QF 31 pounds (14.06 kg), 35 pounds (15.88 kg) from 1944[2]
Calibre4-inch (101.6 mm)
Breechhorizontal sliding-block
ElevationPIX Mount -10° to +20°
CPIII Mount -10° to +30°[1]
Muzzle velocityMk IV : 2,370 feet per second (720 m/s)[3]
Mk XII & XXII : 1,873 feet per second (571 m/s)
Maximum firing range11,580 yards (10,590 m) at +30°[1]

Mk IV gun

Mk IV armed many British destroyers and some cruisers in World War I. It was used to arm merchant ships in World War II.

The guns armed the following warships :

Mk XII and XXII submarine gun

The Mk XII variant was developed for arming submarines from 1918, Mk XXII was developed to arm submarines during World War II. These submarine guns fired a heavier 35 pounds (16 kg) projectile from late 1944.[2] Shortly after the end of hostilities, the Mk XXII was superseded in new British submarines by the lighter QF 4 inch Mk XXIII.[4]

Mk XII and XXII equipped submarines

Surviving guns

See also

Weapons of comparable role, performance and era


  1. Mk IV = Mark 4. Britain used Roman numerals to denote Marks (models) of ordnance until after World War II. This was the fourth model of 4-inch QF naval gun. Variants Mk XII = Mark 12, Mk XXII = Mark 22.


  1. Campbell, Naval Weapons of WWII, p.59.
  2. DiGiulian
  3. 2,370 ft/s for Mk IV gun with 31 lb (14 kg) projectile in WWI, using 5 lb 1 oz 12 drams cordite MD size 16 propellant (Treatise on Ammunition, 10th Edition 1915)
  4. "Britain - 4"/33 (10.2 cm) QF Mark XXIII". www.navweaps.com. Tony DiGiulian. 22 October 2008. Retrieved 21 March 2014.


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