4"/40 (10.2 cm) QF Mark XIX
Updated 27 August 2015

Used by many smaller warships during World War II, this was a low-velocity gun intended mainly for use against surfaced submarines.

Constructed of monobloc barrel and shrunk-on breech ring.  Used a horizontal sliding breech block.  A total of 2,023 guns were manufactured, including 1,006 in Canada and 219 in Australia.


HMAS Mildura
Bathurst class minesweeper with 4" (10.2 cm) gun on forecastle


4"/40 (10.2 cm) Mark XIX gun on HMCS New Glasgow about 1944

Library and Archives Canada Photograph 3206297


4"/40 (10.2 cm) Mark XIX gun in Mark XXIII mounting on HMAS Geelong
Note the simple nature of the gunshield

Australian War Memorial photograph ID 075717


4"/40 (10.2 cm) Mark XIX gun on HMAS Cowra
Comparing this mounting with the one above, note that in this later design that a platform for the breech worker and climbing rungs have been added
As in every navy, war experience funneled back to the design bureaus resulted in improvements on new construction

Australian War Memorial photograph ID 109986

Gun Characteristics
Designation 4"/40 (10.2 cm) QF Mark XIX
Ship Class Used On "River" class, "Castle" class, some "Flower" class, Bathurst class, trawlers and DEMS

Used by early "Battle" class destroyers as a starshell gun

Date Of Design About 1938
Date In Service 1939
Gun Weight 2,886 lbs. (1,309 kg)
Gun Length oa 166.6 in (4.232 m)
Bore Length 161.8 in (4.111 m)
Rifling Length 139.9 in (3.553 m)
Grooves (32) 0.037 in deep x 0.270 (0.94 x 6.86 mm)
Lands 0.1227 in (3.117 mm)
Twist Uniform RH 1 in 30
Chamber Volume 265.9 in3 (4.357 dm3)
Rate Of Fire about 15 rounds per minute
Type Fixed
Weight of Complete Round 50.06 lbs. (22.71 kg)
Projectile Types and Weights HE - 35 lbs. (15.88 kg)
Shrapnel - N/A
Illum - N/A
Bursting Charge N/A
Projectile Length N/A
Complete Round was 35.88 in (91.1 cm)
Propellant Charge 1.875 lbs. (0.85 kg) SC048
2.234 lbs. (1.01 kg) NF042
Muzzle Velocity 1,300 fps (396 mps)
Working Pressure 8.25 tons/in2 (1,300 kg/cm2)
Approximate Barrel Life 2,000 rounds with NF 8000
Ammunition stowage per gun
(see Note)
Battle class:  160 star shell
Others:  N/A
Note:  Flashless propellant was provided to ships other than DEMS.  Outfit for escort ships included 10 rounds HE with RDX/TNT filling per gun and 12 to 18 Shark rounds per ship.
Elevation With 35 lbs. (15.88 kg) HE Shell
Range @ 40 degrees 9,700 yards (8,870 m)
Mount / Turret Data
Designation CP Mark XXIII, XXIII* and XXIII**
Weight  N/A
Elevation -10 / +60 degrees
Elevation Rate Manually operated, only
Train 360 degrees
Train Rate Manually operated, only
Gun recoil N/A
Data from
"Naval Weapons of World War Two" and "British Naval Guns 1880-1945 No 17" article in "Warship Volume X" both by John Campbell
"Warships of World War II" by H.T. Lenton and J.J. Colledge
Page History

19 October 2008 - Benchmark
16 January 2010 - Added picture of HMCS New Glasgow
27 August 2015 - Added photographs of HMAS Geelong and HMAS Cowra