7.5"/45 (19 cm) Mark I
Updated 11 February 2012

A Vickers design.  Suffered from "steel choke" and many guns used cannelured rings as a corrective measure.

Constructed of 'A' tube, inner 'A' tube, wire winding nearly full length, 'B' tube and jacket.  There was a shrunk-on collar at the rear end of the 'A' tube and this and a screwed ring at the rear, secured the 'B' tube and jacket longitudinally.  Used a Welin breech mechanism.  Mark I* had a breech ring to which the breech mechanism was attached, the assembly shrunk over the rear end of the 'A' tube and then screwed to the jacket.  Mark I** had a thicker 'A' tube end and a larger diameter breech ring.  These differences apparently replaced the breech ring.  A total of 33 guns were made, including three prototypes.  Of these, 13 are known to have been Mark I* and four were either Mark I* or Mark II**.


Armored Cruiser HMS Devonshire
7.5" (19 cm) guns in bow and forward wing mounts
U.S. Naval Historical Center Photograph # NH 61120

Images at The Vickers Photographic Archive

See photographs 6470 and 6796

Gun Characteristics
Designation 7.5"/45 (19 cm) Mark I
Ship Class Used On Devonshire class and M.26
Date Of Design about 1903
Date In Service 1905
Gun Weight 13.76 tons (14.0 mt)
Gun Length oa 349.2 in (8.870 m)
Bore Length about 375.0 in (9.525 m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist N/A
Chamber Volume N/A
Rate Of Fire 4 -5 rounds per minute
Type Bag
Projectile Types and Weights AP - 200 lbs. (90.7 kg)
Common - 200 lbs. (90.7 kg)
CPC - 200 lbs. (90.7 kg)
HE - 200 lbs. (90.7 kg)
Bursting Charge N/A
Projectile Length N/A
Propellant Charge N/A
Muzzle Velocity 2,765 fps (843 mps)
Working Pressure N/A
Approximate Barrel Life N/A
Ammunition stowage per gun N/A
Note:  Projectiles were 2crh.
Elevation With 200 lbs. (90.7) HE Shell
Range @  15 degrees 14,008 yards (12,810 m)
Note:  Taken from range tables, but "Warship Volume VII" says that these were probably about 200 yards (180 m) too long.
Armor Penetration with 200 lbs. (90.7 kg) CPC Projectile
Range Vertical KC Plate
3,000 yards (2,740 m) 4.5 in (11.4 cm)
Note:  Data from "The Grand Fleet:  Warship Design and Development 1906-1922" for an angle of obliquity of 30 degrees and a striking velocity of 1,640 fps (500 mps).  Projectiles were salt-filled (blind).
Mount / Turret Data
Designation Single Mounts
   Devonshire (4):  CP Mark I
   M.26 (1):  CP Mark III (adapted)
Weight  N/A
Elevation about -5 / +15 degrees
Elevation Rate Manual operation, only
Train Bow and Stern mounts:  about +150 / -150 degrees
Wing mounts:  about +30 / +150 degrees
Train Rate N/A
Gun recoil N/A
Loading Angle N/A
Data from
"Warrior to Dreadnought:  Warship Development 1860-1905" and "The Grand Fleet:  Warship Design and Development 1906-1922" both by D.K. Brown
"British Naval Guns 1880-1945 No 9" article by John Campbell in "Warship Volume VII"
"World Warships in Review 1860-1906" by John Leather
Special help by Daniel Muir
Page History

07 January 2007 - Benchmark
11 February 2012 - Updated to latest template