Military Wiki
Ordnance RML 64 pounder 71 cwt gun (converted)
RML 64 pounder 71 cwt gun Canberra 300px.jpg
No. 398 made by Royal Gun Factory in 1870, at the Royal Australian Artillery Memorial, Canberra
Type Naval gun
Coast defence gun
Place of origin United Kingdom
Service history
In service 1870 - 190?
Used by Royal Navy
Australian Colonies
Production history
Designed 1870
Manufacturer Royal Arsenal
Weight 7,896 pounds (3,582 kg)
Barrel length 103.27 inches (2.623 m) (bore)[1]

Shell 64 pounds (29.03 kg)
Calibre 6.3-inch (160.0 mm)
Muzzle velocity 1,230 feet per second (370 m/s)[2]

The RML 64 pounder 71 cwt guns (converted) were rifled muzzle-loading guns converted from obsolete smoothbore 8-inch 65 cwt shell guns. "71 cwt" refers to the gun's weight rounded up to differentiate it from other "64-pounder" guns : 1 cwt = 112 pounds.


Diagram showing gun barrel dimensions

When Britain adopted rifled ordnance in the 1860s it still had large stocks of serviceable but now obsolete smoothbore guns. Gun barrels were expensive to manufacture, so the best and most recent models were selected for conversion to rifled guns, for use as second-line ordnance, using a technique designed by William Palliser. The Palliser conversion was based on what was accepted as a sound principle that the strongest material in the barrel construction should be innermost, and hence a new tube of stronger wrought iron was inserted in the old cast iron barrel, rather than attempting to reinforce the old barrel from the outside.[1]

This gun was based on the cast-iron barrel of the 8 inch 65 cwt gun, which previously fired a shell weighing 50 pounds. The 8-inch gun was bored out to 10.5 inches and a new built-up wrought iron inner tube with inner diameter of 6.29 inches was inserted and fastened in place. The gun was then rifled with 3 grooves, with a uniform twist of 1 turn in 40 calibres (i.e. 1 turn in 252 inches), and proof fired. The proof firing also served to expand the new tube slightly and ensure a tight fit in the old iron tube.[1]


Broadside guns seen here on British screw corvette HMS Sapphire circa. 1878

This gun was deployed on many smaller British cruising warships around the world, and also as a coast defence gun in British colonial garrisons.

See also

Surviving examples


  1. 1.0 1.1 1.2 Treatise on Construction and Manufacture of Service Ordnance, 1879, pages 233-238, 292
  2. 1,230 feet/second firing 64-pound projectile with charge of 8 pounds gunpowder. Treatise on Construction of Service Ordnance 1879, page 94


External links

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