RML 10 inch 18 ton gun

The RML 10 inch guns Mk I - Mk II were large rifled muzzle-loading guns designed for British battleships and monitors in the 1860s to 1880s. They were also fitted to the Bouncer-class flat-iron gunboats.^[4]

Design

Mk I & MK II gun barrels

The 10-inch gun was a standard "Woolwich" design (characterised by having a steel A tube with relatively few broad, rounded and shallow rifling grooves) developed in 1868, based on the successful Mk III 9-inch gun, itself based on the "Fraser" system. The Fraser system was an economy measure applied to the successful Armstrong design for heavy muzzle-loaders, which were expensive to produce. It retained the Armstrong steel barrel surrounded by wrought-iron coils under tension, but replaced the multiple thin wrought-iron coils shrunk around it by a single larger coil (10 inch Mark I) or 2 coils (Mark II); the trunnion ring was now welded to other coils; and it eliminated Armstrong's expensive forged breech-piece.^[5]

The gun was rifled with 7 grooves, increasing from 1 turn in 100 calibres to 1 in 40.^[2]

It was first used for the main armament on the central battery ironclad HMS Hercules, completed in late 1868.

A number of the Mk I guns on HMS Hercules and one of the two damaged guns in HMVS Cerberus suffered from cracked barrels.^[6] Presumably this is why only a few (at least 25) Mk I guns were made.

Ammunition

When the gun was first introduced projectiles had several rows of "studs" which engaged with the gun's rifling to impart spin. Sometime after 1878, "attached gas-checks" were fitted to the bases of the studded shells, reducing wear on the guns and improving their range and accuracy. Subsequently "automatic gas-checks" were developed which could rotate shells, allowing the deployment of a new range of studless ammunition. Thus, any particular gun potentially operated with a mix of studded and studless ammunition.

The gun's primary projectile was "Palliser" shot or shell, an early armour-piercing projectile for attacking armoured warships. A large "battering charge" of 70 pounds "P" (pebble) or 60 pounds "R.L.G." (rifle large grain) gunpowder^[7] was used for the Palliser projectile to achieve maximum velocity and hence penetrating capability.

Common (i.e. ordinary explosive) shells and shrapnel shells were fired with the standard "full service charge" of 44 pounds "P" or 40 pounds R.L.G. gunpowder,^[7] as for these velocity was not as important.

• 

  Studless Palliser shell, 410 lb, 1886
• 

  Studless Common shell, 410 lb, 1886
• 

  Studless Shrapnel shell, 410 lb, 1886

See also

• List of naval guns

Surviving examples

One of the guns on top of Fort St Catherine, Bermuda

• 4 guns submerged near the remains of HMVS Cerberus in Half Moon Bay, Victoria, Australia (3 x Mk I & 1 x Mk II)
• Damaged Mk I gun No. 17 from HMVS Cerberus is on display at HMAS Cerberus Victoria, Australia
• Mk II gun No. 67 at Southport Gates, Gibraltar
• A Mk II gun at Parson's Lodge Battery, Gibraltar
• Mk II No. 273 at Almeda Gardens, Gibraltar
• Mk II guns Several guns at Fort St Catherine, St George's Island, Bermuda (at least three are Mk II guns)
• A Mk II at the Citadel, Quebec City, Canada

One 10 inch Mk I Common Shell, one 10 inch Mk II Common Shell & one 10 inch Mk III Palliser Shot as part of the Victorian Navy display at the Geelong Maritime Museum, Australia. Details

Various other guns are mounted or unmounted in Bermuda, with some lying outside of Fort St Catherine, having been rolled out when made obsolete (the guns actually mounted on display there were taken from other forts, notably Fort Albert), and a number having been found buried in the moat of Fort Cunningham (the two mounted at Fort George are the RML 11 inch 25 ton gun). At least one has been erected on a display stand at Fort Hamilton, though the original mount is missing, and another at Alexandia Battery.

Notes and references

Bibliography

• Treatise on the construction and manufacture of ordnance in the British service. War Office, UK, 1877
• Treatise on Ammunition. 2nd Edition 1877. War Office, UK.
• Manual for Victorian naval forces 1887. HMVS Cerberus website
• Treatise on Ammunition, 4th Edition 1887. War Office, UK.
• Sir Thomas Brassey, The British Navy, Volume II. London: Longmans, Green and Co. 1882

External links

Wikimedia Commons has media related to RML 10 inch 18 ton Gun.

• Diagram of gun on Casemate Traversing Platform, at Victorian Forts website
• Diagram of gun on Dwarf "D" Pivot mounting, at Victorian Forts website
• Diagram of gun on 7 foot Parapet "C" mounting, at Victorian Forts website
• Diagram of gun on 7 foot Parapet "C" Long Range mounting, at Victorian Forts website

British Empire naval weapons of the Victorian era Smoothbore muzzle-loading cannons 18-pounder 24-pounder 32-pounder 58 cwt 68-pounder Somerset cannon Smoothbore muzzle-loading shell guns 8 inch 10-inch 86 cwt Mortars 10-inch Blomefield 13-inch Blomefield Howitzers 12-pounder Millar 24-pounder Millar Rifled breechloaders (Armstrong) RBL 9 pounder RBL 20 pounder RBL 40 pounder RBL 7 inch 110 pounder Rifled muzzle-loaders (Lancaster) 68-Pounder Lancaster gun Rifled muzzle-loaders (converted) RML 64 pounder 71 cwt Rifled muzzle-loaders (Woolwich) RML 9 pounder 8 cwt RML 64 pounder 64 cwt RML 7 inch RML 8 inch RML 9 inch RML 10 inch RML 11 inch RML 12 inch 25 ton RML 12 inch 35 ton RML 12.5 inch RML 16 inch Quick-firing guns QF 3-pounder Hotchkiss QF 6-pounder Hotchkiss QF 6 pounder Nordenfelt QF 12-pounder 12 cwt Mk I QF 4 inch QF 4.7 inch QF 6 inch Breech-loaders (new pattern) BL 4 inch BL 5 inch BL 6 inch 80 pounder BL 6 inch Mk II – VI BL 8 inch BL 9.2 inch Mk I – VII BL 9.2 inch Mk VIII BL 10 inch BL 12 inch Mk I – VII BL 12 inch Mk VIII BL 13.5 inch BL 16.25 inch Light weapons Gatling gun Gardner gun Nordenfelt gun 1-inch Nordenfelt gun Torpedoes Whitehead torpedo