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Gunning for Glasgow as Navy’s first 5in gun is installed on new frigate

An artist's impression of HMS Glasgow at sea
6 September 2024
The first next-generation gun has been installed on the first of the Royal Navy’s next-generation warships.

Fitted on the forecastle of HMS Glasgow – the lead ship in the class of Type 26 frigates under construction on the Clyde – is a 5in gun which is likely to be the mainstay of the Fleet for half a century or more.

Glasgow and her seven City-class sisters are designed primarily to be submarine hunters, replacing the existing force of Type 23 frigates from later this decade into the 2030s.

But they are expected to carry out other roles – through adaptable mission bays which will allow the City class to operate autonomous equipment such as drones, mine hunting systems or raiding kit for commandos, to more traditional tasks like pummelling enemy positions with shellfire.

The weapon – officially the Mk45 Mod 4A Medium Calibre Gun – is the latest variant of a US Navy gun which is fitted to more than 280 warships in 11 navies including those of Australia, New Zealand, Japan and several NATO allies.

It succeeds the existing Mk8 4.5in – the Royal Navy’s medium gun of choice since the early 1970s, fitted to all frigates and destroyers, and which has served the Royal Navy well in the Falklands, two Gulf wars and the Libyan Civil War.

Why the change? Well, its successor is fully automated, safer, reliable, accurate, interoperable with our closest NATO allies and able to eliminate threats as varied as enemy positions ashore or aerial drones.
This is a major milestone for the Type 26 MOD Weapons team and the Type 26 BAE Naval Ships Gunnery team. The Mk 45 Mod 4 is a proven, effective weapon that incorporates the latest technologies for today’s multi-mission warships

Neil Stevenson, Type 26 Weapons Group Leader at Defence Equipment and Support

On HMS Glasgow, it’s still without its barrel (to be fitted in due course), so right now the gun resembles a large grey fridge covered by protective plastic sheeting.

But once operational… Depending on the ammunition and propellant used, shells (weighing up to 31½kg) leave the muzzle at speeds between 823 and 1,051 metres per second – 1,841-2,351 mph or 2½ to 3 times the speed of sound.

In addition to traditional naval gunfire support, the 5in can be accurately brought to bear against aerial threats (including drones) and fast-moving inshore attack craft (and a shell is considerably cheaper than using a missile). 

While the gun itself is impressive, it’s what is beneath it in HMS Glasgow’s forecastle which truly marks it out from its predecessor: the automatic handling system.

Based on a system used in the US Navy’s futuristic Zumwalt-class destroyers but designed specifically for the Type 26s, it means sailors no longer need form a chain to supply the gun with fresh shells during a shoot – as they do with the current 4.5in weapon.

Instead, the automatic system pulls in shells from the ‘deep magazine’ to constantly re-fill the 20-round ‘ready to use’ magazine which feeds the gun (should the automatic system fail or be damaged in action, it can be re-loaded manually).

Automation makes the new weapon safer: there’s no requirement to lift heavy shells, deal with moving machinery, risk injury to hearing from the clangs and bangs as the gun fires. 

The net result say experts is a first-class medium gun which packs a punch in extremes of weather, day or night, is easier to maintain, operates seamlessly working with allies and is highly reliable – other navies report an availability of 99.6 per cent. 

The gun was installed at BAE’s Scotstoun facility on the Clyde, watched by HMS Glasgow’s nascent ship’s company.

“This is a major milestone for the Type 26 MOD Weapons team and the Type 26 BAE Naval Ships Gunnery team. The Mk 45 Mod 4 is a proven, effective weapon that incorporates the latest technologies for today’s multi-mission warships,” said Neil Stevenson, Type 26 Weapons Group Leader at Defence Equipment and Support.

“Throughout the entire team has been supported by US Department of Defense and the Royal Navy, ensuring that this system is at the forefront of gunnery technology and adaptability, that meets the needs of the Royal Navy, now and in the future.”

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