The Mk 45 Mod 4A Medium Calibre Gun on HMS Glasgow, the first Type 26 frigate, is capable of firing 5-inch shells weighing up to 31.5 kg at speeds between 1,841 and 2,351 mph—up to Mach 3, or three times the speed of sound, UK Defence Journal reports.
With an effective range of up to 37 km (20 nautical miles), the Mk 45 Mod 4A is not just about power but precision.
The system can be used for traditional naval gunfire support, pummelling enemy positions ashore, and is also equipped to handle fast-moving inshore attack craft and aerial threats, including drones.
One of the most remarkable features of the Mk 45 Mod 4A is its fully automated ammunition handling system. Traditionally, sailors were required to manually form a chain to load shells into the gun, a labour-intensive and potentially dangerous process.
The new system, however, automates this task, drawing on technology first used in the US Navy’s Zumwalt-class destroyers. It ensures a continuous supply of shells from the ship’s deep magazine to the gun’s 20-round ready-to-use magazine, significantly reducing the crew’s workload.
This automated system also enhances reliability, with other navies reporting that the Mk 45 Mod 4A achieves a 99.6% availability rate. In the event of a failure in the automatic system, the gun can still be manually reloaded, ensuring its operational capabilities are maintained even in extreme conditions. The absence of manual handling also makes the system safer for the crew, as there’s no need to lift heavy shells or work around moving machinery, which reduces the risk of injury from the noise and vibrations caused by the gun’s firing.
The design of the Mk 45 Mod 4A also includes a longer barrel than its predecessors, which allows for more complete propellant combustion, increasing the velocity and range of the projectiles. This makes the gun particularly effective for land-attack missions, where precision and range are critical. Additionally, the system’s radar signature has been reduced thanks to a modified flat-panel gun turret, making it harder for enemy forces to detect.
HMS Glasgow is the first of eight City-class frigates set to replace the Royal Navy’s ageing Type 23 fleet.
According to Neil Stevenson, Type 26 Weapons Group Leader at Defence Equipment and Support, “The Mk 45 Mod 4 is a proven, effective weapon that incorporates the latest technologies for today’s multi-mission warships.”
