|Ordnance QF 4 inch gun Mk XVI|
Twin Mk XVI on HMCS Haida
Naval anti-aircraft gun
|Place of origin||United Kingdom|
|Used by||Royal Navy|
Royal Canadian Navy
Royal Australian Navy
South African Navy Royal Malaysian Navy
|Wars||World War II|
|Variants||Mk XVI* and Mk XXI|
|Mass||Barrel & breech 4,495 lb (2,039 kg)|
|Barrel length||180 inches (4,572 mm) (45 cal)|
|Shell||Fixed QF 35 pounds (15.88 kg) HE|
38.25 pounds (17.35 kg) S.A.P.
|Calibre||4-inch (101.6 mm)|
|Recoil||hydro - pneumatic 831 millimetres (33 in)|
|Elevation||mounting dependent (-10 to 80 deg on H.A. twin mark XIX mount)|
|Rate of fire||15-20 rounds per minute|
|Muzzle velocity||2,660 feet per second (811 m/s)|
|Maximum firing range||19,850 yards (18,150 m) at 45 degrees elevation|
AA Range: 39,000 feet (11,890 m) at 80 degrees elevation
|Filling weight||9 pounds (4.08 kg)|
The Mk XVI superseded the earlier QF 4 inch Mk V naval gun on many Royal Naval ships during the late 1930s and early 1940s. The ammunition fired by the Mk V gun and the Mk XVI guns was different. The Mk V ammunition was 44.3 inches (1.13 m) long and weighed 56 pounds (25 kg), while the ammunition fired by the Mk XVI gun was 42.1 inches (1.07 m) long and weighed 66.75 pounds (30.28 kg). The weight of the high-explosive projectile grew from 31 pounds (14 kg) for the Mk V to 35 pounds (16 kg) for the Mk XVI.
There were three variants of the gun produced with differing construction methods. The original Mk XVI had an A tube, jacket to 63.5 inches (1.61 m) from the muzzle and a removable breech ring. The Mk XVI* replaced the A tube with an autofretted loose barrel with a sealing collar at the front of the jacket. The Mk XXI was a lighter version with an autofretted monobloc barrel and a removable breech ring. The total number of Mk XVI and XVI* guns produced was 2,555 while there were 238 Mk XXI guns produced. Of those totals 604 Mk XVI* and 135 of the Mk XXI guns were produced in Canada and 45 of the Mk XVI* were produced in Australia. These guns were usually mounted on HA/LA Mark XIX twin mountings, although several Australian frigates and corvettes had single-gun Mk XX mountings.
The last Royal Navy ship to operate with a Mark XIX twin mounting was HMS Mermaid , which had originally been designed for the Ghana Navy and so required a simple and inexpensive main armament. Acquired by the British Government in 1972, she served until 1977 when she was purchased by the Royal Malaysian Navy and renamed KD Hang Tuah.
Twin guns of HMAS Swan bombarding shore positions in New Guinea, February 1945
Single Mk XX mounting on HMAS Barcoo, 1945
Gunners of HMS Glasgow clearing empty cartridges after a shoot