These were coast defense guns developed by the Army for use against German Schnellboots ("E-boats") and other small craft. Twenty-two of them were transferred to the Navy and used on old destroyers detailed for coastal escort duties.

Constructed of A tube, part length jacket and breech ring. Used a semi-automatic sliding breech block.

Gun Characteristics

Designation 6-pdr / 10cwt QF Mark I
Ship Class Used On Campbell, Mackay, Montrose, Whitshed, Wivern, Worcester, Walpole and Windsor
Date Of Design N/A
Date In Service 1941 in naval service
Gun Weight 1,060 lbs. (481 kg)
Gun Length oa 109.7 in (2.787 m)
Bore Length 105.5 in (2.679 m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist N/A
Chamber Volume 73.5 in3 (1.2 dm3)
Rate Of Fire 18 rounds per minute


Type Fixed
Weight of Complete Round N/A
Projectile Types and Weights HE: 6.28 lbs. (2.85 kg)
HE-T: 6.54 lbs. (2.97 kg)
Bursting Charge N/A
Projectile Length N/A
Propellant Charge 1.27 lbs. (0.576 kg) N 045
Muzzle Velocity HE: 2,386 fps (727 mps)
HE-T: 2,356 fps (718 mps)
Working Pressure N/A
Approximate Barrel Life N/A
Ammunition stowage per gun N/A
  • ^Outfits were half HE and half HE-T (tracer).


Range during World War I with 6.28 lbs. (2.85 kg) HE
Elevation Distance
45 degrees 11,300 yards (10,330 m)

Mount/Turret Data

  • Twin Mounts
    • Coastal Defense: Mark I
    • Destroyers (1): Mark I*
Weight N/A
Elevation -10 / +80 degrees
Elevation Rate Manually operated, only
Train 360 degrees
Train Rate Manually operated, only
Gun recoil 12 in (30.5 cm)

The naval mounting had a more extensive shield than did the coast defense mounting.

Additional Pictures


Data from:

  • "Naval Weapons of World War Two" by John Campbell
  • "Warships of World War II" by H.T. Lenton and J.J. Colledge

Special help from Dave Alton and Richard Worth

Page History

16 October 2005
12 February 2012
Updated to latest template
15 December 2013
Added photographs of HMS Mackay