RML 8-inch 9-ton gun

The British RML 8-inch 9-ton guns Mark I – Mark III^[5] were medium rifled muzzle-loading guns used to arm smaller ironclad warships and coast defence batteries in the later 19th century.

RML 8-inch 9-ton gun
Gundeck of HMS Northumberland
Type	Naval gun Coast defence gun
Place of origin	United Kingdom
Service history
In service	1866–190?
Used by	Royal Navy
Production history
Manufacturer	Royal Arsenal
Unit cost	£568[1]
Variants	Mk I – Mk III
Specifications
Mass	9 long tons (9.1 t)
Barrel length	118 inches (3.0 m) bore + chamber[2]
Shell	174 pounds 12 ounces (79.3 kg)[3]
Calibre	8-inch (203.2 mm)
Muzzle velocity	1,420 feet per second (430 m/s)[4]

Design

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 in (810 cm)) at the muzzle.

Ammunition

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.^[6]

See also

• List of naval guns

Surviving examples