4"/33 (10.2 cm) QF Mark XXIII
Updated 29 November 2015

A light weight gun for submarines.  Developed too late for service during World War II.

Constructed with a monobloc loose barrel and breech ring.  The bore and external parallel section were nickel plated and zinc protective plates were on the breech ring and horizontal sliding breech block.  A total of thirty-one guns were manufactured.  Actual bore length was 33.04 calibers.


4"/33 (10.2 cm) gun from HMS Andrew now at the Royal Navy Submarine Museum, Gosport, Hampshire, UK
Photograph copyrighted by Geni


Plaque for above gun
Notable items on this plaque are the following:  "HMS Andrew was the last Royal Navy Submarine to be equipped with a deck gun for surface action" and "The gun was last fired on 2 December 1974"
Photograph copyrighted by Geni

Images at The Vickers Photographic Archive


Gun Characteristics
Designation 4"/33 (10.2 cm) QF Mark XXIII
Ship Class Used On A class and a few T class submarines
Date Of Design about 1944
Date In Service 1946
Gun Weight 0.7 tons (0.76 mt)
Gun Length oa 137.6 in (3.495 m)
Bore Length 132.2 in (3.358 m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist N/A
Chamber Volume 183 in3 (3.00 dm3)
Rate Of Fire about 15 rounds per minute
Type Fixed
Projectile Types and Weights HE - 35 lbs. (15.9 kg)
HE - 38.5 lbs. (17.5 kg)
Bursting Charge N/A
Projectile Length N/A
Propellant Charge 3.75 lbs. (1.7 kg) NF052
3.88 lbs. (1.8 kg) NF052
Muzzle Velocity For 35 lbs. (15.9 kg) - 1,791 fps (546 mps)
For 38.5 lbs. (17.5 kg) - 1,745 fps (532 mps)
Working Pressure N/A
Approximate Barrel Life N/A
Ammunition stowage per gun N/A
Elevation With 35 lbs. (15.9 kg) HE Shell
Range @ 30 degrees 12,080 yards (11,050 m)
Mount / Turret Data
Designation Single Mounting
   Submarines (1):  SII
Weight  N/A
Elevation -5 (?) / +30 degrees
(may have later been altered to +20 degrees)
Elevation Rate Manually operated, only
Train 360 degrees
Train Rate Manually operated, only
Gun recoil N/A
Data from
"British Naval Guns 1880-1945 No 18" article by John Campbell in "Warship Volume X"
Special help by Rod Butcher
Page History

22 October 2008 - Benchmark
12 February 2012 - Updated to latest template
29 November 2015 - Changed Vickers Photographic Archive links to point at Wayback Archive