4.5 inch Mark 8 naval gun

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4.5 inch Mark 8 naval gun
4.5 inch Mk 8 Mod 1 naval gun on HMS Northumberland. The multi-faceted gunhouse is designed to reduce radar cross section.
Type Naval gun
Place of origin  United Kingdom
Service history
In service 1972 - present
Wars Falklands war
Production history
Designer Mod 0 : Royal Armament Research and Development Establishment
Mod 1 : Royal Ordnance Defence
Variants Mod 0, Mod 1
Barrel length 244.75 inches (6.217 m) bore (55 calibres)

Shell Fixed QF 46 pounds (21 kg) HE
Calibre 4.45-inch (113 mm)[1]

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


The 4.5 inch gun has been the standard medium-gun calibre 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 actually 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, 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 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, therefore needing fewer people than its predecessors to operate. 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 operates the aiming and firing process. The weapon 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.

These guns proved to be less reliable than the older 4.5 inch Mark 6 (Mark V gun) during the Falklands War, being forced to cease fire on several occasions due to faults.[2]

The first major modification to the mounting, the MOD 1, was developed in the late 1990's; 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.[3][4]

155mm variant

The Ministry of Defence (MoD) is investigating a proposal from BAE Systems to "up gun" the 4.5 inch to accept the 155 mm gun barrel and breech from the AS-90 self propelled gun.[5] This would introduce a common gun calibre with the British Army and Royal Navy, helping with ammunition logistics, and encouraging joint Army-Navy development of extended range and precision guided shells.[6] A £4m contract has been awarded to develop a prototype, and firing trials had been scheduled for 2009.[7]



See also


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External links

  1. 1.0 1.1 Jane's Ammunition Handbook, 1999-2000 Edition. http://www.janes.com
  2. Navweaps.com
  3. Photo Gallery : HMS Richmond : Type 23 Frigates : Surface Fleet : Operations and Support : Royal Navy
  4. Navy News - News Desk - News - From South Wales to the West Indies
  5. 155MM Study Looks To Pack More Punch Into The Royal Navy's Fleet BAe Systems Press release, 14 December 2007
  6. Army to get new precision "search and destroy" anti-armour weapon MoD Press release, 20 November 2007
  7. "Royal Navy Prepares to Roll out the Big Guns". Royal Navy. 2008-08-28.