RML 8-inch 9-ton gun
|RML 8-inch 9-ton gun|
Gundeck of HMS Northumberland
Coast defence gun
|Place of origin||United Kingdom|
|Used by||Royal Navy|
|Variants||Mk I – Mk III|
|Mass||9 long tons (9.1 t)|
|Barrel length||118 inches (3.0 m) bore + chamber|
|Shell||174 pounds 12 ounces (79.3 kg)|
|Calibre||8-inch (203.2 mm)|
|Muzzle velocity||1,420 feet per second (430 m/s)|
In common with other Royal Ordnance RML designs of the 1860s, Mark I used the strong but expensive Armstrong system of a steel tube surrounded by a complex system of multiple wrought-iron coils, which was progressively simplified in Marks II and III to reduce costs : Mark III consisted only of A tube, B tube, breech coil and cascabel screw.
Rifling was of the "Woolwich" pattern of a small number of broad shallow grooves: 4 grooves with twist increasing from 0 to 1 turn in 40 calibres (i.e. in 320 inches) at the muzzle.
The ammunition was mainly studded, with the studs engaging in the Woolwich rifling grooves. However, a studless pointed common shell with automatic gas-check also became available later in the gun's life.
Notes and references
- Unit cost of £567 12 shillings 10 pence is quoted in "The British Navy" Volume II, 1882, by Sir Thomas Brassey. Page 38
- Text Book of Gunnery 1887 Table XVI page 313
- 174 lb 12 oz projectile. Text Book of Gunnery 1887 Table XVI page 313
- 1,420 feet/second firing 174-pound 12-oz projectile . Text Book of Gunnery 1887 Table XVI page 313
- Mark I – Mark III = Mark 1 through to Mark 3. Britain used Roman numerals to denote Marks (models) of ordnance until after World War II. Hence this article describes the three models of RML 8-inch guns.
- Gas-checks in British RML heavy guns
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