4.5-inch Mark 8 naval gun

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4.5-inch Mark 8 naval gun
HMS DEFENDER fires her 4.5-inch Mk 8 Mod 1 naval gun MOD 45157963.jpg
4.5-inch Mk 8 Mod 1 naval gun on HMS Defender. The multi-faceted gunhouse is designed to reduce radar cross section.
TypeNaval gun
Place of originUnited Kingdom
Service history
In service1972 – present
WarsFalklands War
Invasion of Iraq 2003
2011 military intervention in Libya
Production history
DesignerMod 0 : Royal Armament Research and Development Establishment
Mod 1 : Royal Ordnance Defence
VariantsMod 0, Mod 1
Barrel length244.75 inches (6.217 m) bore (55 calibres)

Shell113 x 700mmR
Fixed QF 46 pounds (21 kg) HE
Calibre4.45-inch (113 mm)[1]
Maximum firing range27.5 kilometres (17.1 mi)[2]

The 4.5 inch Mark 8 is a British naval gun system which currently equips the Royal Navy's destroyers and frigates, and some British destroyers and frigates sold to other countries.


Guns with a 4.5 inch calibre have been the standard medium-calibre gun of the Royal Navy for use against surface, aircraft and shore targets since 1938. The current 55-calibre Mark 8 gun replaced the World War II era 45-calibre QF 4.5-inch Mk I – V naval guns. Like all British 4.5 inch naval guns, it has a calibre of 4.45 inches (113 mm).[1]


A completely new type of 4.5 inch gun with a longer 55-calibre barrel, it was designed in the 1960s for the Royal Navy's new classes of frigates and destroyers. The new weapon, built by Vickers Ltd Armament Division, was developed by the Royal Armament Research and Development Establishment using the Ordnance, QF 105 mm L13 of the Abbot self-propelled gun as a starting point (it used electrical primers). The outer shell of the gunhouse is built from glass-reinforced plastic (GRP).

The new weapon emphasised reliability and rapid response to fire first round from shutdown state (particularly for defence against missiles)[3] over a high rate of fire, allowing a switch to a lighter, single barrel mounting and ammunition of a one-piece design.

The gun system has a combination of electrical and hydraulic components and the full system penetrates up to three deck levels below the weather deck; deep magazine, gun control room and power room, gunbay and the gunhouse.

The weapon is semi-automatic and can be operated by a smaller crew than its predecessors. With no personnel in the gunhouse, loading is supported by personnel in the gunbay to load the feed ring and in the deep-magazine to pass ammunition to the gunbay. The captain of the gun in the control room ensures continued weapon readiness and the gun controller in the operations room aims and fires the weapon. The gun has a rate of fire of about 25 rounds per minute and a range of 12 nm (22 km; 27.5 km with the newer High Explosive Extended Range round).

The first recipient of the new gun and mount, the Mark 8, was the Iranian frigate Zaal in 1971. The gun entered Royal Navy service in 1973 on the new destroyer Bristol.[4]

These guns proved to be less reliable than the older 4.5 inch Mark V gun (redesignated Mark 6 gun mounting) during the Falklands War, being forced to cease fire on several occasions due to faults.[3]

The first major modification to the mounting, the Mod 1, was developed in 1998 in two tranches;[4] replacing the gunhouse with a reduced radar cross section assembly and replacing the hydraulic loading mechanism with an all-electric system. This particular gun has been nicknamed the "Kryten gun" by members of Royal Navy, after the odd shaped head of a robot from the British Sci-fi comedy series Red Dwarf.[5][6] Babcock upgraded 13 guns to Mod 1 standard between 2005 and 2012.[7]



  • Weight of complete round - 80.5 lbs. (36.5 kg)
  • Length of complete round - 48.7 in (123.8 cm)
  • Projectile weight - 45.4 lbs. (20.6 kg)
  • Bursting charge - 6.6 lbs. (3 kg) RDX/TNT (60/40)
  • Propellant charge - 15.8 lbs. (7.15 kg)
  • Muzzle velocity - 2,850 fps (869 mps)
  • Cartridge case - Brass, 114 x 700 mm R

HE N4A1 :

  • Weight of complete round - 80.5 lbs. (36.5 kg)
  • Length of complete round - 48.7 in (123.8 cm)
  • Projectile weight - 46 lbs. (20.9 kg)
  • Bursting charge - N/A
  • Propellant charge - 15.8 lbs. (7.15 kg)
  • Muzzle velocity - 2,850 fps (869 mps)
  • Cartridge case - Brass, 114 x 700 mm R[3]

155 mm variant[edit]

The Ministry of Defence investigated a proposal from BAE Systems to adapt the 4.5 inch system to accept the heavier calibre 155 mm (6.1 inch) gun barrel and breech from the AS-90 self-propelled gun.[8] This "155mm Third Generation Maritime Fire Support" (155 TMF) would introduce a common gun calibre for the British Army and Royal Navy, helping with ammunition logistics, and encouraging joint Army-Navy development of extended range and precision guided shells.[9] A £4m contract was awarded to develop a prototype, and firing trials were scheduled for 2009[10] with delivery in 2014,[4] but the project was cancelled in the cuts implemented following the 2010 Strategic Defence and Security Review.

Operational history[edit]

In 2011, the Royal Navy's HMS Iron Duke used its Mk 8 gun to destroy a gun battery outside of the besieged town of Misrata, Libya,[11][12] while HMS Liverpool used its Mk 8 gun to destroy a shore battery that had fired missiles at her.[13][14]


Although the Mk 8 was fitted to the Type 45 destroyer, on the Type 26 frigate it will be supplanted by the BAE 5-inch Mk 45 naval gun.[15]



See also[edit]

Weapons of comparable role, performance and era[edit]


  1. ^ a b Jane's Ammunition Handbook, 1999–2000 Edition. http://www.janes.com/
  2. ^ HMS Collingwood takes delivery of Gate Guard
  3. ^ a b c "4.5"/55 (11.4 cm) QF Mark 8 Mod 0 and Mod 1". NavWeaps. Retrieved 1 August 2022.
  4. ^ a b c McClure, Robert. "155 Third Generation Maritime Fire Support (155 TMF)" (PDF). BAE Systems Global Combat Systems. Archived from the original (PDF) on 19 July 2013. Retrieved 25 September 2012.
  5. ^ Photo Gallery : HMS Richmond : Type 23 Frigates : Surface Fleet : Operations and Support : Royal Navy
  6. ^ "Navy News – News Desk – News – From South Wales to the West Indies". Archived from the original on 21 February 2004. Retrieved 17 April 2008.
  7. ^ "Gun contract completes" (PDF). DESider. Ministry of Defence. September 2012. p. 10.
  8. ^ 155MM Study Looks To Pack More Punch into The Royal Navy's Fleet Archived 12 February 2012 at the Wayback Machine BAe Systems Press release, 14 December 2007
  9. ^ Army to get new precision "search and destroy" anti-armour weapon Archived 11 December 2007 at the Wayback Machine MoD Press release, 20 November 2007
  10. ^ "Royal Navy Prepares to Roll out the Big Guns". Royal Navy. 28 August 2008. Archived from the original on 15 October 2008. Retrieved 28 August 2008.
  11. ^ "UK: HMS Iron Duke, HMS Richmond Return to Portsmouth". worldmaritimenews.com. 29 July 2011. Retrieved 14 March 2020.
  12. ^ "HMS Iron Duke honoured for efficiency on operations". gov.uk. 7 March 2012. Retrieved 14 March 2020.
  13. ^ "HMS Liverpool fires on Gaddafi forces". gov.uk. 13 May 2011. Retrieved 14 March 2020.
  14. ^ Harding, Thomas (4 August 2011). "Libya: Royal Navy warship HMS Liverpool comes under heavy fire". TheGuardian.com. Retrieved 14 March 2020.
  15. ^ "£183 million deal signed for Type 26 Frigate gun", UK Defence Journal, 28 July 2016


External links[edit]