|Ordnance QF 4 inch gun Mk XXIII|
Mk XXIII gun from HMS Andrew at the Royal Navy Submarine Museum, Gosport.
|Type||Submarine deck gun|
|Place of origin||United Kingdom|
|Used by||United Kingdom|
|Weight||1,568 pounds (711 kg) barrel & breech|
|Length||137.6 inches (3.495 m)|
|Barrel length||132.2 inches (3.358 m) bore (33 calibres)|
|Shell||Fixed QF 35 pounds (15.88 kg)|
38.5 pounds (17.46 kg)
|Calibre||4-inch (101.6 mm)|
|Breech||horizontal sliding block|
|Carriage||Submarine SII mounting|
|Elevation||-5 to +30 degrees|
|Rate of fire||about 15 rounds per minute|
|Muzzle velocity||35 lb: 1,791 feet per second (546 m/s)|
38.5 lb: 1,745 feet per second (532 m/s)
|Maximum range||35 lb @ 30 degrees: 12,080 yards (11,050 m)|
Development and service
Development of the Mark XXIII began in 1942, as a lighter replacement for the QF 4-inch gun Mark XXII, which was based on a gun introduced in 1911. It was too late to see service in World War II, but was fitted to Amphion-class submarines that completed after October 1945. It was also fitted to some T-class submarines.
Between 1955 and the early 1960s, the Amphion-class boats were modernised with new streamlined conning towers and casings. This work included the removal of the deck gun, although the underlying supports for the gun mountings were retained in case they were required. This facility was put to use during the British involvement in the Indonesia–Malaysia confrontation from 1962 to 1966, when the flotilla of Amphion-class submarines which were deployed in the conflict were again fitted with Mark XXIII guns. These were used to counter blockade-running Indonesian junks and other small vessels. HMS Andrew retained her gun into the 1970s; the last firing was on 2 December 1974.
- Lambert, John. "Naval Weapons, Equipment, Fittings & Boats.". John Lambert Plans. http://www.feralchicken.co.uk/lambert-plans/encom/naval_weapons_comp.htm. Retrieved 21 March 2014.
- Akermann, Paul (2002), Encyclopedia of British Submarines 1901-1955, Periscope Publishing Limited, ISBN 1-904381-05-7 (pp. 426-427)
- Whitman, Edward C (Summer 2003). "Royal Navy Submarine Museum". Undersea Warfare - The Official Magazine of the U.S. Submarine Force. http://www.navy.mil/navydata/cno/n87/usw/issue_19/royal_navy2.htm. Retrieved 21 March 2014.
- Technical drawing of the 4-in. QF MARK XXIII Gun on 4-in. S2 (Submarine) Mounting (John Lambert Plans and Drawings)
- HMS Andrew gun removal, 1975 photograph on Flickr.
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