Britain
9.2"/40 (23.4 cm) Mark VIII
Updated 31 January 2009
Early cocoa-powder gun used on 1st class Protected Cruisers.  Later used in coast defense batteries at Cromarty in 1913-1914.

Constructed of inner A tube/A tube/wire over rear half of A/jacket and B tube to 150 in ( cm) from muzzle/trunnion hoop over join jacket and B hoop.  The breech bush screwed into the A tube and a collar between the A tube and the jacket screwed into the latter.  The breech block was an interrupted screw cylindrical type with a hand worked continuous mechanism.  The Mark VIII* indicated an alteration to the front slope to prevent slip back at high elevations, but no guns were so modified.

Actual bore length was 40.08 calibers.  A total of six guns were made.
WNBR_92-40_mk8_Powerful_pic.jpg

HMS Powerful in 1898
The 9.2" (23.4 cm) guns are in the bow and stern mounts
Photograph by Beken of Cowes
WNBR_92-40_mk8_gun_pic.jpg

Constructional view of 9.2"/40 (23.4 cm) Mark VIII
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Gun Characteristics
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Designation 9.2"/40 (23.4 cm) Mark VIII
Ship Class Used On Powerful class
Date Of Design about 1895
Date In Service 1897
Gun Weight 25 tons (26 mt)
Gun Length oa 384 in (9.754 m)
Bore Length 368.7 in (9.366 m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist N/A
Chamber Volume 4,600 in3 (75.4 dm3)
Rate Of Fire about 2 rounds per minute
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Ammunition
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Type Bag
Projectile Types and Weights CPC 2crh - 380 lbs. (172.4 kg)
Bursting Charge CPC - 35.4 lbs. (16.1 kg)
Projectile Length CPC - 35.4 in (89.9 cm)
Propellant Charge 66 lbs. (29.9 kg) Cord 40+3.75
77.25 lbs. (35.0 kg) MD37
Muzzle Velocity 2,329 fps (710 mps) [Cord propellant]
Working Pressure N/A
Approximate Barrel Life N/A
Ammunition stowage per gun N/A
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Range
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Elevation With 380 lbs. (172.4 kg) CPC Shell
15 degrees 12,846 yards (11,745 m)
Note:  Taken from range tables, but John Campbell calls this figure "optimistic."
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Mount / Turret Data
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Designation Single mounts
   Powerful (2):  CPIV
Weight  N/A
Elevation -5 / +15 degrees
Elevation Rate N/A
Train about +150 / -150 degrees
Train Rate N/A
Gun recoil N/A
Loading Angle N/A
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Data from
"Big Gun Monitors:  The History of the Design, Construction and Operation of the Royal Navy's Monitors" by Ian Buxton
"British Naval Guns 1880-1945 No 6" article by John Campbell in "Warship Volume VI"
"World Warships in Review 1860-1906" by John Leather
Article in Brasseys Naval Annual
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Special help from George Gratz and Daniel Muir
Page History

05 August 2006 - Benchmark
31 January 2009 - Added construction details