# 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The Mk XVI superseded the earlier QF 4 inch Mk V naval gun on many Royal Navy ships during the late 1930s and early 1940s. The ammunition fired by the Mk V gun and the Mk XVI guns were different. The ammunition for the Mk V gun 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 (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.

## List of equipped vessels
### As secondary armament

(list not complete)
* Aircraft carriers: HMS Furious, HMS Unicorn
* Escort carriers: Nairana-class escort carriers, HMS Pretoria Castle, HMS Activity
* HMS Hood
* C-class cruisers (converted to anti-aircraft cruisers)
* HMS Barham, HMS Malaya, HMS Warspite
* Revenge-class battleships
* County-class cruisers
* HMS Exeter
* Swiftsure-class cruisers
* Crown Colony-class cruisers
* Edinburgh-class cruisers
* Southampton-class cruisers
* Arethusa-class cruisers
* Perth-class cruisers
* Leander-class cruisers
* HMS Effingham
* HMS Danae
* 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 (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 Britain

* ORP Błyskawica (Polish)
* HNLMS Jacob van Heemskerck (Dutch)
* HNLMS Isaac Sweers (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 mount on their foredeck between 1955 and 1976.

## Ammunition

* 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
* Gunners of V-class destroyer HMS Vivien displaying anti-aircraft rounds, 1940
* A round in a fuze setter on HMS Belfast