QF 4-inch naval gun Mk XXIII

Ordnance QF 4 inch gun Mk XXIII
Mk XXIII gun from HMS Andrew at the Royal Navy Submarine Museum, Gosport.
Type	Submarine deck gun
Place of origin	United Kingdom
Service history
In service	1945-1974
Used by	United Kingdom
Wars	Indonesia–Malaysia confrontation Cold War
Production history
Produced	1945-46
No. built	31
Specifications
Mass	1,568 lb (711 kg) barrel and breech
Length	137.6 in (3.495 m)
Barrel length	132.2 in (3.358 m) bore (33 calibres)
Shell	Fixed QF 35 lb (15.9 kg) 38.5 lb (17.5 kg)
Calibre	4 in (102 mm)
Breech	horizontal sliding-block
Carriage	4-0 Inch SII Mounting
Elevation	-10 to +30 degrees
Traverse	360 degrees[1]
Rate of fire	about 15 rounds per minute
Muzzle velocity	35 lb: 1,791 ft/s (546 m/s) 38.5 lb: 1,745 ft/s (532 m/s)
Maximum firing range	12,080 yd (11.05 km) 35 lb HE shell at 30 degrees:

The QF 4-inch gun Mark XXIII was introduced in late 1945 as a deck gun for Royal Navy submarines. It was the last type of gun to be fitted to British submarines, finally being retired in 1974.