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

Ordnance QF 4 inch gun Mk IV, XII, XXII
Origin:	United Kingdom
Type:	Light Naval gun Submarine gun
Is Ranged:	yes
Is Artillery:	yes
Is Uk:	yes
Service:	1911-1940s
Used By:	United Kingdom
Wars:	World War I World War II
Number:	1,141^[1]
Weight:	2750lb barrel & breech
Part Length:	160inches bore (40 calibres)
Cartridge:	Mk IV : Separate QF 31lb; Mk XII & XXII : Fixed QF 31lb, 35lb from 1944^[2]
Caliber:	4adj=onNaNadj=on
Velocity:	Mk IV : 2370ft/s^[3] Mk XII & XXII : 1873ft/s
Max Range:	11580yd at +30°^[4]
Breech:	horizontal sliding-block
Elevation:	PIX Mount -10° to +20° CPIII Mount -10° to +30°^[5]

The QF 4-inch gun Mk IV^[6] 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.^[7] Mk XII and Mk XXII variants armed many British interwar and World War II submarines.

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 :

• Forward-class scout cruisers as re-gunned in 1911
• Sentinel-class scout cruisers as re-gunned 1911-1912
• Pathfinder-class scout cruisers as re-gunned 1911-1912
• Adventure-class scout cruisers as re-gunned 1911-1912
• Acasta (K)-class destroyers of 1911
• Laforey (L)-class destroyers of 1913
• Yarrow M-class destroyers laid down 1912 - 1915
• Admiralty M-class destroyer of 1913
• Thornycroft M-class destroyers laid down 1913 - 1915
• Hawthorn M-class destroyer of 1914
• s of 1914
• s of 1914
• Faulknor-class leaders of 1914
• s of 1914
• Parker class leaders of 1915
• Yarrow Later M-class destroyers of 1915
• R-class destroyers of 1916
• S-class destroyers of 1917
• s of 1938 (guns from decommissioned Canadian S-class destroyers)

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 35lb projectile from late 1944. Shortly after the end of hostilities, the Mk XXII was superseded in new British submarines by the lighter QF 4 inch Mk XXIII.^[8]

Mk XII and XXII equipped submarines

• L class
• Odin ("O") class
• Parthian ("P") class
• River (or Thames) class
• Grampus (or Porpoise) class
• Triton ("T") class
• S class
• Some of the Amphion ("A" or Acheron) class

Surviving guns

• The Mk IV gun from which fired the first British shot of World War I on 5 August 1914 is on display at the National Museum of the Royal Navy, Portsmouth (on loan from the Imperial War Museum).^[9]
• A Mk IV gun on a 1945 Mk XVI mounting is on display at the Heugh Gun Battery Museum in Hartlepool, County Durham.^[10]
• A Mk IV gun on a pedestal mounting is still in situ at Ordnance Point in the Falkland Islands, where it is believed to have been installed in 1943.^[11]
• A First World War 4-inch naval gun, tentatively identified as a Mk IV, stands outside the Army, Navy and Air Force Veterans Hall in 4th Street, Sidney, British Columbia.^[12]

See also

• List of naval guns

Weapons of comparable role, performance and era

• 10.5 cm SK L/45 naval gun : German WWI equivalent
• 10.5 cm SK C/32 naval gun : Slightly more powerful German equivalent WWII submarine gun
• 4"/50 caliber gun : US Navy equivalent

Sources

• Tony DiGiulian, British 4"/40 (10.2 cm) QF Marks IV, XII and XXII
• Book: Campbell, John . Naval Weapons of World War Two . Naval Institute Press . Annapolis, MD . 1985 . 0-87021-459-4.

Notes and References

1. Campbell, Naval Weapons of WWII, p.59.
2. DiGiulian
3. 2,370 ft/s for Mk IV gun with 31lb projectile in WWI, using 5 lb 1 oz 12 drams cordite MD size 16 propellant (Treatise on Ammunition, 10th Edition 1915)
4. Campbell, Naval Weapons of WWII, p.59.
5. Campbell, Naval Weapons of WWII, p.59.
6. 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.
7. Campbell, Naval Weapons of WWII, p.59.
8. Web site: Britain - 4"/33 (10.2 cm) QF Mark XXIII . 22 October 2008 . www.navweaps.com . Tony DiGiulian . 21 March 2014.
9. Web site: GUN WHICH FIRED THE FIRST SHOT AT SEA IN WW1 IS INSTALLED FOR NEW £4.5M REMEMBRANCE GALLERY . . 2014 . www.nmrn.org.uk . National Museum of the Royal Navy . 2 January 2022.
10. Web site: Hartlepool in County Durham, England, United Kingdom - Naval Gun 4 inch . . www.hmdb.org . Historical Marker Database . 28 December 2021.
11. Web site: British Coastal Defences of the Falkland Islands . . frontlineulster.co.uk . Frontline Ulster . 28 December 2021.
12. Book: Skaarup, Harold A. . 2012 . Shelldrake: Canadian Artillery Museums and Gun Monuments . Bloomington, IN . iUniverse . 2–3 . 978-1469750002.