British 10"/32 (25.4 cm) Marks I, II, III and IV

British
10"/32 (25.4 cm) Marks I, II, III and IV
Updated 07 January 2007

A series of trunnioned guns used in coastal artillery and late 19th century fighting vessels.

The Mark I was an Elswick design used only in coastal batteries and was not interchangeable with the other Marks. The other Marks were Woolwich designs which were used afloat but were mainly utilized for coastal defense batteries world-wide. These other Marks were interchangeable with each other and the ships that carried them eventually had a complement of different Marks.

All Marks were of complex built up construction and used a cylindrical interrupted screw breech block with a hand worked 3-motion mechanism, although HMS Renown was reported to have a continuous motion mechanism in 1897. Altogether, ten Mark I, five Mark II, fifty-two Mark III and nine Mark IV guns were manufactured.

Nomenclature note: The 10" (25.4 cm) Mark V was a proposed 50-caliber gun of 1901 that was never built.

After 10-in (25.4 cm) guns on HMS Renown
Legend on top of shield is "England expects that every man will do his duty" [Lord Nelson]
This is an open-backed gun shield. Note the depression rail on top of the barbette, which kept the guns from firing into the ship's structure.
IWM Photograph

Gun Characteristics .

Designation	10"/32 (25.4 cm) Marks I, II, III and VI
Ship Class Used On	Victoria, Thunderer, Devastation and Barfleur classes
Date Of Design	Mark I: 1884 Mark II: 1885 Mark III: 1888 Mark IV: 1889/1890
Date In Service	1885
Gun Weight	Mark I: 32.32 tons (32.8 mt) Others: 29.53 tons (30 mt)
Gun Length oa	342.4 in (8.697 m)
Bore Length	320 in (8.128 m)
Rifling Length	N/A
Grooves	N/A
Lands	N/A
Twist	N/A
Chamber Volume	8,370 in³ (137.2 dm³)
Rate Of Fire	about 0.5 rounds per minute

Ammunition .

Type	Bag
Projectile Types and Weights	AP - 500 lbs. (227 kg)
Bursting Charge	N/A
Projectile Length	N/A
Propellant Charge	Full charge: 252 lbs. (114.3 kg) Pr Br, 76-cord 30 Half charge: 126 lbs. (57.15 kg) Pr Br, 76-cord 30
Muzzle Velocity	Full charges: 2,040 fps (622 mps) Half charges: 1,393 fps (425 mps)
Working Pressure	N/A
Approximate Barrel Life	N/A
Ammunition stowage per gun	105 rounds
Note: Half charges were only used at higher elevations. See Mount / Turret note, below.

Range .

Elevation	With 500 lbs. (227 kg) AP Shell
Range @ 12.1 degrees (Full charges)	10,100 yards (9,235 m)
Range @ 35 degrees (Half charges) See note below	11,552 yards (10,560 m)

Armor Penetration with 500 lbs. (227 kg) Projectile .

Range	Vertical Iron Plate
1,000 yards (9,140 m)	20.4 in (51.8 cm)
Note: Data from "British Battleships: 1850 - 1950."

Mount / Turret Data .

Designation	Single Mount Victoria (2): VCP I Twin Mounts Thunderer (2): Turret Mark I Devastation (2): Turret Mark II Barbette Mount Barfleur class (2): Barbette Mark III
Weight	N/A
Elevation	VCP1: 0 / +14 degrees Mark I: 0 / +12 degrees Mark II: 0 / +13 degrees Mark III: 0 / +15 degrees (see note)
Elevation Rate	N/A
Train	+150 / -150 degrees
Train Rate	N/A
Gun recoil	N/A
Loading Angle	N/A
Note: The Barbette Mark III mounting was partly steam and partly electric or hand worked and 35 degree elevation could be achieved if a section of the shield was removed. However, only half charges could be fired at this elevation, converting the gun into a type of howitzer.

Data from
"Warrior to Dreadnought: Warship Development 1860-1905" by D.K. Brown
"British Naval Guns 1880-1945 No 5" article by John Campbell in "Warship Volume VI"
"British Battleships: 1850 - 1950" by Oscar Parkes