QF 4-inch naval gun Mk XVI

The QF 4 inch Mk XVI gun was the standard British Commonwealth naval anti-aircraft and dual-purpose gun of World War II.

Service
The Mk XVI superseded the earlier QF 4 inch Mk V naval gun on many Royal Naval ships during the late 1930s and early 1940s.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 in long and weighed 56 lb, while the ammunition fired by the Mk XVI gun was 42.1 in long and weighed 66.75 lb. The weight of the high-explosive projectile grew from 31 lb for the Mk V to 35 lb 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 in 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 (F76), 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.

As secondary armament (list not complete)

 * Aircraft carriers: HMS Furious (47), HMS Unicorn (I72)
 * Escort carriers: Nairana-class escort carriers, HMS Pretoria Castle, HMS Activity
 * HMS Hood (51)
 * C-class cruisers (converted to anti-aircraft cruisers)
 * HMS Barham (04), HMS Malaya, HMS Warspite (03)
 * Revenge-class battleships
 * County-class cruisers
 * HMS Exeter (68)
 * Swiftsure-class cruisers
 * Crown Colony-class cruisers
 * Edinburgh-class cruisers
 * Southampton-class cruisers
 * Arethusa-class cruisers
 * Perth-class cruisers
 * Leander-class cruisers
 * HMS Effingham (D98)
 * HMS Danae (D44)
 * Roberts-class monitor

As main armament (list not complete)

 * Abdiel-class minelayers
 * Tribal-class destroyers
 * L and M-class destroyer (the first series L: HMS Gurkha, Lance, Legion, Lively)
 * HMS Petard (G56) (modified)
 * Weapon-class destroyers
 * V and W-class destroyers (after WAIR modification – 15 ships)
 * HMS Wallace (after WAIR modification)
 * Hunt-class destroyers
 * Some Bathurst-class corvettes (single-gun Mk XX mounting)
 * Black Swan-class sloops
 * Egret-class sloops
 * Bittern-class sloop (modified)
 * Grimsby-class sloop (modified)
 * Bay-class frigates
 * River-class frigates (part of Canadian-built)
 * 8 auxiliary AA defence ships
 * Some landing ships

Allied ships fitted out in the United Kingdom

 * ORP Błyskawica (Polish)
 * HNLMS Jacob van Heemskerck (1939) (Dutch)
 * HNLMS Isaac Sweers (1940) (Dutch)
 * 4 French Elan-class avisos and Chamois-class avisos

Post-war construction ships

 * Type 15 frigates (converted)
 * Type 16 frigates (converted)
 * SAS Jan van Riebeeck and Simon van der Stel converted frigates (South Africa)
 * NNS Nigeria frigate (Nigerian)
 * Vosper Mk 3 corvettes (NNS Dorina and Otobo) (Nigerian)

The South African Navy Loch-class frigates (HMSAS Good Hope and HMSAS Transvaal) each had two of these guns mounted on a twin Mark XIX on their foredeck between 1955 and 1976.

Surviving examples

 * On HMCS Haida (G63), Hamilton, Ontario, Canada.
 * A pair in turret from HMCS Huron (G24) at the Royal Military College, Kingston, Ontario, Canada
 * Naval Museum of Alberta, Canada
 * HMCS Unicorn, Saskatoon, Saskatchewan, Canada.
 * Trenton Park, Trenton, Nova Scotia, Canada
 * On HMS Belfast (C35), London, which retains four twin guns.
 * Explosion! Museum of Naval Firepower, Gosport, Hampshire, UK
 * On ORP Błyskawica, Gdynia (re-bored to 100 mm).
 * A pair at South African National Museum of Military History, Johannesburg
 * A pair in a turret from INS Haifa (K-38), at Clandestine Immigration and Naval Museum, Haifa, Israel.
 * Two single guns on HMAS Diamantina (K377), Brisbane, Australia
 * One twin gun at the Marinemuseet, Horten, Norway.
 * One twin gun in the Aldhurst military vehicles collection, Surrey England. Further research has proven the left gun was installed on the heavy cruiser HMS Devonshire from 1943 till she was scrapped in 1954.