The Mark VI was an Elswick gun of Pattern "S" originally built for six Chilean destroyers of the Almirante Lynch class, but four of these destroyers were taken over by the British at the start of World War I. Post-war, the three surviving destroyers were given back to Chile.

The Mark X was a single Elswick gun of Pattern "Q" similar in design and performance to the Mark VI. The Mark X was probably never used afloat.

Mark VI constructed of A tube, breech piece and B tube, wire over the breech piece, full length jacket, breech ring and breech bush screwed into the breech piece. Used a screw breech block whose design was similar to that for the QF Mark III. A total of 29 Mark VI guns were manufactured.

Gun Characteristics

Designation 4"/40 (10.2 cm) QF Mark VI
Ship Class Used On Britain: Faulknor class, Swordfish and Mimosa
Chile: Almirante Lynch class (ex-Faulknor class)
Date Of Design N/A
Date In Service about 1914
Gun Weight 1.297 tons (1.41 mt)
Gun Length oa 165.1 in (4.194 m)
Bore Length about 160 in (4.064 m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist N/A
Chamber Volume 240 in3 (3.933 dm3)
Rate Of Fire about 15 rounds per minute


Type Separate
Projectile Types and Weights HE: 31 lbs. (14.06 kg)
Bursting Charge N/A
Projectile Length N/A
Propellant Charge 5.0 lbs. (2.27 kg) MD16
Muzzle Velocity 2,300 fps (701 mps)
Working Pressure N/A
Approximate Barrel Life N/A
Ammunition stowage per gun N/A


Range with 31 lbs. (14.06 kg) HE
Elevation Distance
25 degrees 11,630 yards (10,630 m)

Mount/Turret Data

Designation Single Mounting
   Faulknor (6) 1, Mimosa (1 or 2) and Swordfish (N/A): PXI
Weight N/A
Elevation -5 (?) / +25 degrees
Elevation Rate Manually operated, only
Train 360 degrees
Train Rate Manually operated, only
Gun recoil N/A


"Naval Weapons of World War Two" and "British Naval Guns 1880-1945 No 18" article in "Warship Volume X" both by John Campbell

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25 March 2008 - Benchmark
12 February 2012 - Updated to latest template
11 December 2021 - Converted to HTML 5, added photograph of HMS Botha