4"/40 (10.2 cm) QF Mark VI and Mark X
Updated 12 February 2012

The Mark VI was an Elswick gun of Pattern "S" originally built for 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.

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Gun Characteristics
Designation 4"/40 (10.2 cm) QF Mark VI
Ship Class Used On Britain:  Broke class, Swordfish and Mimosa
Chile:  Almirante Lynch class (ex-Broke 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
Elevation With 31 lbs. (14.06 kg) HE Shell
Range @ 25 degrees 11,630 yards (10,630 m)
Mount / Turret Data
Designation Single Mounting
   Broke (6), 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
Note:  Survivors of the Broke class were rearmed with 4.7"/45 (12 cm) BL Mark I guns during World War I.
Data from
"British Naval Guns 1880-1945 No 18" article by John Campbell in "Warship Volume X"
Page History

25 March 2008 - Benchmark
12 February 2012 - Updated to latest template