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.

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: 35.88 in (91.1 cm)
Propellant Charge 1 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 2 Battle class: 160 star shell
Others: N/A
  • ^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.


Range with 35 lbs. (15.88 kg) HE
Elevation Distance
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

Additional Pictures


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

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Added picture of HMCS New Glasgow
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Added photographs of HMAS Geelong and HMAS Cowra