QF 4.5-inch Mk I – V naval gun

The QF 4.5 inch gun has been the standard medium-calibre naval gun used by the Royal Navy as a medium range weapon capable of use against surface, aircraft and shore bombardment targets since 1938. This article covers the early 45-calibre family of guns up to the 1970s. For the later unrelated 55-calibre Royal Navy gun, see 4.5 inch Mark 8 naval gun.

Like all British nominally 4.5 inch naval guns, the QF Mk I has an actual calibre of 4.45 inches (113 mm).

Country Name Origin Year
United Kingdom - UK (Great Britain) 1938
Country Name Operational Year Retirement Year
United Kingdom - UK (Great Britain) View

The QF 4.5 inch L/45 was developed originally as a dual-purpose weapon with which to arm aircraft carriers and reconstructed battleships and battlecruisers. It was later developed as a new dual-purpose weapon with which to arm destroyers, supplanting the ubiquitous 4.7 inch gun. Despite the lower calibre, it actually had a heavier shell, resulting in a more powerful weapon.

Type Naval gun
Anti-aircraft gun
Place of origin United Kingdom
Service history
Used by British Commonwealth
Wars Second World War
Korean War
Falklands War
Production history
Number built Navy: c. 800
Army: 474
Barrel length Bore: 16 ft 8 in (5.08 m)
45 calibres
Shell Fixed or Separate QF 55 pounds (24.9 kg)
Calibre 4.45-inch (113 mm)
Breech Mks I - IV: Horizontal sliding block
Mk V: Vertical sliding block
Rate of fire 12 RPM for Mk II BD mount. 16 RPM recorded for Mk III UD mount.
Muzzle velocity 2,449 ft/s (746 m/s)
Maximum firing range 20,750 yd (18,970 m) at 2,449 ft/s (746 m/s)
AA:41,000 ft (12,500 m)

End notes