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 and

flat-iron gunboat Flat-iron gunboats (more formally known as Rendel gunboats) were a number of classes of coastal gunboats generally characterised by small size, low freeboard, the absence of masts,Some Rendel-type gunboats were fitted with masts (the British ''Med ...

s. They were also used for fixed coastal defences around the United Kingdom and around the British Empire until the early years of the 20th century.

Design

The 10-inch gun was a standard "

Woolwich Woolwich () is a district in southeast London, England, within the Royal Borough of Greenwich. The district's location on the River Thames led to its status as an important naval, military and industrial area; a role that was maintained thr ...

" 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. The gun was rifled with 7 grooves, increasing from 1 turn in 100 calibres to 1 in 40. It was first used for the main armament on the central battery ironclad , 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.HMVS Cerberus website. reports of cracked guns
/ref> 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 Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, carbon (in the form of charcoal) and potassium nitrate (saltpeter). Th ...

Treatise on Ammunition 1877, page 220 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, as for these velocity was not as important. Studded RML 10-inch shell Southsea Castle UK.jpg, Studded RML 10-inch shell Sothsea Castle UK - 1.jpg, RML 10-inch Palliser studless shell Mk II diagram.jpg, RML 10-inch Common studless shell Mk I diagram.jpg, RML 10-inch Shrapnel studless shell Mk I diagram.jpg,

Surviving examples

RML 10-inch Mk II gun closeup Fort St Catherine

* 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
Mark II gun No.35
at Parson's Lodge Battery, Gibraltar
Mark II gun no.38 at
York Redoubt, Halifax, Canada * Mark II gun No. 67 at Southport Gates,

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* Mk II guns Mark II guns numbers 156, 180 (dated 1871), 195, 221 and 224 at Fort St. Catherine, St George's Island, Bermuda (Guns were originally from Fort Albert)
Mark II No. 273
at Almeda Gardens, Gibraltar
Mark II guns, numbers 338, 340, 342, 356 and 357, dated 1878
Fort Cunningham, Paget Island, Bermuda
A Mark II at the Citadel, Quebec City, Canada
* A single gun at Chapel Bay Fort, United Kingdom 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 RML 11-inch 25-ton guns were large Muzzle-loading rifle, rifled muzzle-loading guns used as primary armament on British battleships and for coastal defence. They were effectively the same gun as the RML 12-inch 25-ton gun, bored to 11 inches inste ...

). Three have been erected on concrete display stands at Fort Hamilton, though the original mounts are missing, and another at Alexandria 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

Handbook for the 10-inch rifled muzzle-loading gun of 18 tons, 1899
at State Library of Victoria
"Handbook for the 10-inch R.M.L. Guns (Land Service)", 1903, London. Published by His Majesty's Stationery Office
at State Library of Victoria

External links