The RML 9-inch guns Mark I – Mark VIMark I – Mark VI = Mark 1 through to Mark 6. Britain used

Roman numerals Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Numbers are written with combinations of letters from the Latin alphabet, ...

to denote Marks (models) of ordnance until after World War II. Hence this article describes the six models of RML 9-inch guns. were large rifled muzzle-loading guns of the 1860s used as primary armament on smaller British ironclad battleships and secondary armament on larger battleships, and also ashore for coast defence. It should not be confused with the RML 9-inch Armstrong Gun, used by the Dutch navy, the Spanish Navy, and other navies.

Design

The

rifling In firearms, rifling is machining helical grooves into the internal (bore) surface of a gun's barrel for the purpose of exerting torque and thus imparting a spin to a projectile around its longitudinal axis during shooting to stabilize the ...

was the Woolwich pattern of a relatively small number of broad, rounded shallow grooves : there were 6 grooves, increasing from 0 to 1 turn in 45 calibres (i.e. 405 inches). Mark I, introduced in 1865, incorporated the strong but expensive

Armstrong Armstrong may refer to: Places * Armstrong Creek (disambiguation), various places Antarctica * Armstrong Reef, Biscoe Islands Argentina * Armstrong, Santa Fe Australia * Armstrong, Victoria Canada * Armstrong, British Columbia * Armstrong, ...

method of a steel A tube surrounded by multiple thin wrought-iron coils which maintained the central A tube under compression, and a forged steel breech-piece. 190 were made.Treatise on Construction of Service Ordnance 1877, pages 92–93 and 277–280 Mark II in 1866 incorporated the modified Fraser design. This was an economy measure, intended to reduce the costs incurred in building to the Armstrong design. It incorporated fewer but heavier wrought-iron coils but retained the Armstrong forged breech-piece. Only 26 were made. Mark III in 1866–1867 eliminated the Armstrong forged breech piece and hence fully implemented the Fraser economy design. It consisted of only 4 parts : steel A tube, cascabel, B tube and breech coil. 136 were made. Mark IV, introduced 1869, and V incorporated a thinner steel A tube and 2 breech coils. The explanation for separating the heavy breech coil of Mk III into a coiled breech piece covered by a breech coil was "the difficulty of ensuring the soundness of the interior of a large mass of iron".

Mk VI high-angle gun

In the late 1880s and early 1890s a small number of guns were adapted as high-angle coast defence guns around Britain : known battery locations were Tregantle Down Battery at Plymouth,

Verne High Angle Battery The Verne High Angle Battery is a former 19th-century gun battery on the Isle of Portland in Dorset, England. Situated close to the Verne Citadel, the battery is Grade II Listed, and forms part of the citadel's scheduled monument status. The batt ...

at Portland and

Steynewood Battery Steynewood Battery (map reference ) is a battery located between Bembridge and Whitecliff Bay on the Isle of Wight, England. It is one of the many Palmerston Forts The Palmerston Forts are a group of forts and associated structures around the ...

at Bembridge on the

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. The idea behind these high-angle guns was that the high elevation gave the shell a steep angle of descent and hence enabled it to penetrate the lightly armoured decks of attacking ships rather than their heavily armoured sides. To increase accuracy the old barrels were relined and given modern polygroove rifling : 27 grooves with a twist increasing from 1 turn in 100 calibres to 1 turn in 35 calibres after 49.5 inches. These guns fired a special 360-pound armour-piercing shell to a range of 10,500 yards using a propellant charge of 14 lb Cordite Mk I size 7½, remained in service through

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...

and were not declared obsolete until 1922.Hogg & Thurston 1972, page 158-159 Some guns were bored out and relined in 10-inch calibre. A battery of six such guns is known to have been mounted at

Spy Glass Battery Spy Glass Battery or Spyglass Battery was originally a high angle artillery battery in the British Overseas Territory of Gibraltar. The battery is mounted high on the rock to give extra range and protection. The battery was still in use during the ...

on the

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, and six guns at Gharghur, Malta.

Ammunition

The projectiles of RML 9-inch guns Marks I-V (the Woolwich rifled guns) 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 Mark VI high-angle gun had polygroove rifling, and was only able to fire studless ammunition, using a different automatic gas-check from the one used with Marks I-V. The gun's primary projectile was Palliser shot or shell, an early armour-piercing projectile for attacking armoured warships. A large battering charge of 50 pounds P (pebble) or 43 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). T ...

Treatise on Ammunition 1877, page 220 was used for the Palliser projectile to achieve maximum velocity and hence penetrating capability.

Common Common may refer to: Places * Common, a townland in County Tyrone, Northern Ireland * Boston Common, a central public park in Boston, Massachusetts * Cambridge Common, common land area in Cambridge, Massachusetts * Clapham Common, originally ...

(i.e. ordinary explosive) shells and

shrapnel shell Shrapnel shells were anti-personnel artillery munitions which carried many individual bullets close to a target area and then ejected them to allow them to continue along the shell's trajectory and strike targets individually. They relied almo ...

s were fired with the standard full service charge of 30 pounds R.L.G. gunpowder or 33 pounds P (pebble) gunpowder, as for these velocity was not as important. RML 9-inch 12-ton Common Shell Diagram 1872.jpg, RML 9-inch studded common shell with gascheck diagram.jpg, RML 9-inch studless common shell with rotating gascheck diagram.jpg, RML 9-inch studless palliser shell with rotating gascheck diagram.jpg,

Surviving examples

Mark I Number 14, dated 1865 on

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Mark I Number 22 at Middle North Battery, Simon's Town, South Africa, and still being fired.

Mark I Number 127 dated 1867, Castle Field
Wicklow
Mark I Number 148 dated 1867

Fort St. Catherine Fort St. Catherine, or ''Fort St. Catherine's'' (as it is usually referred to), is a coastal artillery fort at the North-East tip of St. George's Island, in the Imperial fortress colony of Bermuda. Successively redeveloped, the fort was used fir ...

, Bermuda * Mark I guns at Apostles Battery, St Lucia
Mark III and Mark IV guns Needles Old Battery, Isle of Wight, UK

A Mark III gun from the Needles Old Battery, now outside Southsea Castle, Portsmouth, UK
* Mark III gun, ex-Needles battery, now at Hurst Castle, Hampshire, UK * Mark III gun, ex-Needles battery, now at Fort Brockhurst, Hampshire, UK * Mark III gun, ex-Needles battery, now at Fort Widley, Hampshire, UK
Mark III Number 272 dated 1868
Alexander battery, St George, Bermuda * Mark V gun,

Harwich Redoubt Harwich Redoubt is a circular fort built in 1808 to defend the port of Harwich, Essex from Napoleonic invasion. The Harwich Society opens it to the public. Construction The Redoubt was built between 1808 and 1810 to protect the port of Harw ...

, Essex, UK * Mark V gun of 1872 at Whampoa, Kowloon, Hong Kong
Mark V Number 589, dated 1872 on

Mark V Number 592
at South Head, Sydney, Australia
Mark V Number 650, dated 1877
at

York Redoubt York Redoubt is a redoubt situated on a bluff overlooking the entrance to Halifax Harbour at Ferguson's Cove, Nova Scotia, Canada, originally constructed in 1793. It was designated a National Historic Site of Canada in 1962. History York Redoub ...

, Halifax, Canada
MK I No. 1670 of 1867
at Fort Queenscliff, Victoria, Australia
No.s 1679 & 1683
at The Strand, Williamstown, Victoria, Australia * No.s 1669 & 1675 at Fort Gellibrand, Victoria, Australia
at York Redoubt National Historic Site, Halifax, Nova Scotia, Canada

A gun at The Citadel, Quebec, Canada

Notes

References

Bibliography

Treatise on the construction and manufacture of ordnance in the British service. War Office, UK, 1877

Text Book of Gunnery, 1887. LONDON : PRINTED FOR HIS MAJESTY'S STATIONERY OFFICE, BY HARRISON AND SONS, ST. MARTIN'S LANE

Text Book of Gunnery, 1902. LONDON : PRINTED FOR HIS MAJESTY'S STATIONERY OFFICE, BY HARRISON AND SONS, ST. MARTIN'S LANE

Treatise on Ammunition. 2nd Edition 1877. War Office, UK.

Treatise on Ammunition, 4th Edition 1887. War Office, UK.
* Sir Thomas Brassey
The British Navy, Volume II. London: Longmans, Green and Co. 1882
* I.V. Hogg & L.F. Thurston, British Artillery Weapons & Ammunition 1914–1918. London: Ian Allan, 1972. * Alexander Lyman Holley
''A Treatise on Ordnance and Armor'' published by D Van Nostrand, New York, 1865
*

at Victorian Forts website
" Handbook for the 9-inch rifled muzzle-loading gun of 12-tons Marks I to VIc", 1894, London. Published by Her Majesty's Stationery Office

External links

* ttp://www.victorianforts.co.uk/art/9RML1.htm Diagram of gun on Casemate A Pivot mounting, at Victorian Forts website
Diagram of gun on C Pivot, at Victorian Forts website

{{DEFAULTSORT:RML 09-inch gun Naval guns of the United Kingdom 230 mm artillery Victorian-era weapons of the United Kingdom Coastal artillery