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**.
| 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 | 3.5 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 | 61.0 lbs. (27.7 kg) 26 Cordite MD |
| Muzzle Velocity | 2,765 fps (843 mps) |
| Working Pressure | N/A |
| Approximate Barrel Life | 600 rounds |
| Ammunition stowage per gun | 120 rounds |
Projectiles were 2crh.
| Elevation | Distance |
|---|---|
| 15 degrees | 14,000 yards (12,800 m) |
Values taken from range tables, but "Warship Volume VII" says that these were probably about 200 yards (180 m) too long.
| Range | Vertical KC Plate |
|---|---|
| 3,000 yards (2,740 m) | 4.5 in (11.4 cm) |
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).
| Designation | Single Mounts
Devonshire (4): CP Mark I M.26 (1): CP Mark III (adapted) |
|---|---|
| Weight | CP Mark I: 87 tons (88.4 mt) |
| Elevation | -7 / +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 |
Mountings were hydraulically worked. Hoists could supply four rounds per minute.
The Vickers Photographic Archive
See photographs 6470
and 6796
"Warrior to Dreadnought: Warship Development 1860-1905" and "The Grand Fleet: Warship Design and Development 1906-1922" both by D.K. Brown
"British Naval Gun Mountings: From 1890: 18-inch to 4.5-inch Mark 8" by Ian Buxton
"British Naval Guns 1880-1945 No 9" article by John Campbell in "Warship Volume VII"
"World Warships in Review 1860-1906" by John Leather
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Special help by Daniel Muir
07 January 2007 - Benchmark
11 February 2012 - Updated to latest template
01 December 2015 - Changed Vickers Photographic Archive links to point at Wayback Archive
20 January 2025 - Converted to HTML 5 format, minor additions to Ammunition and Mount/Turret sections