RML 64 pounder 71 cwt gun

Ordnance RML 64 pounder 71 cwt gun (converted)
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
Specifications
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 British rifled muzzle-loading guns converted from obsolete smoothbore 8-inch 65 cwt shell guns.^{[note 1]}

Design

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]

Deployment

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. It became obsolete from Naval use in the 1880s, with many of the guns being used to equip coast defences in Britain and the Empire. It became obsolete for coast artillery use in 1902, whereupon most of them were scrapped and disposed of.

See also

• RML 64 pounder 64 cwt gun the equivalent new design frontline 64-pounder gun
• List of naval guns

Surviving examples

• Dartmouth Old Battery, Devon, UK
• A gun from 1872 at Southsea Castle, UK
• No. 142 of 1869 at St Helier, Jersey
• 2 guns, No. 398 and 407 at the Royal Australian Artillery Memorial, Mount Pleasant, Canberra, Australia
• A gun at Mays Hill Cemetery, Parramatta, New South Wales, Australia
• A gun outside the wardroom at HMNZS Philomel, Auckland, New Zealand
• A gun on a locally-made carriage at Army Memorial Museum, Waiouru, New Zealand

Notes

1. "71 cwt" refers to the gun's weight rounded up to differentiate it from other "64-pounder" guns : 1 cwt = 112 pounds.

References

1. 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

Bibliography

• Treatise on the Construction and Manufacture of Ordnance in the British Service. War Office, UK, 1879

External links

• WL Ruffell, RML 64-pr 71-cwt