RML 7 inch gun
Encyclopedia
The RML 7 inch guns were various designs of medium-sized rifled muzzle-loading guns used to arm small-medium sized British warships in the late 19th century, and some were used ashore for coast defence.
system, a modification of the French system, of from 3 - 9 broad shallow grooves after Britain abandoned the Armstrong "shunt" rifling system in May 1865 : "...M.L. 7-inch guns in course of manufacture were rifled on this principle, upon which all all our heavy pieces since have been rifled. The 7-inch referred to, and introduced into the service in 1865, were the first of the so-called Woolwich guns, which then meant "wrought iron M.L. guns built up on Sir W. Armstrong's principle, improved upon by hooking the coils over one another, and having solid ended steel barrels, rifled on the system shown above, for studded projectiles".
All versions were constructed of a steel A tube surrounded by various numbers and thicknesses of wrought-iron coils. Rifling was 3 grooves with a uniform 1 turn in 35 calibres i.e. in 245 inches.
The diagrams below show the progression from the original expensive Armstrong construction in Mk I of multiple relatively thin coils, through to the simplified and cheaper Woolwich design of Mk III.
This was a coast defence gun introduced in 1865 to replace the failed RBL 7 inch Armstrong gun.
The following warships were armed with the gun :s in commission from 1865
) low-powered naval gun introduced in 1874 as a broadside gun on unarmoured vessels, and not intended for attacking armour plate. Early models were made by simply turning off some of the jacket around 7-inch 6½ ton guns, as firing with reduced charges placed less strain on the coils. Some new guns were made to similar design.
The following warships were armed with the gun :s in commission from 1874
for attacking armoured warships, fired with a large "battering" charge for maximum velocity. All guns were also equipped with shrapnel shells for anti-personnel use and explosive common shells for attacking unarmoured targets. The "double" common shell was much longer than the standard common shell, and hence contained approximately twice as much gunpowder. It was unstable in flight and hence inaccurate beyond 2,000 yards but was considered useful for attacking wooden warships at ranges below 2,000 yards.
Design and history
These guns were the first to incorporate the new "Woolwich" riflingRifling
Rifling is the process of making helical grooves in the barrel of a gun or firearm, which imparts a spin to a projectile around its long axis...
system, a modification of the French system, of from 3 - 9 broad shallow grooves after Britain abandoned the Armstrong "shunt" rifling system in May 1865 : "...M.L. 7-inch guns in course of manufacture were rifled on this principle, upon which all all our heavy pieces since have been rifled. The 7-inch referred to, and introduced into the service in 1865, were the first of the so-called Woolwich guns, which then meant "wrought iron M.L. guns built up on Sir W. Armstrong's principle, improved upon by hooking the coils over one another, and having solid ended steel barrels, rifled on the system shown above, for studded projectiles".
All versions were constructed of a steel A tube surrounded by various numbers and thicknesses of wrought-iron coils. Rifling was 3 grooves with a uniform 1 turn in 35 calibres i.e. in 245 inches.
The diagrams below show the progression from the original expensive Armstrong construction in Mk I of multiple relatively thin coils, through to the simplified and cheaper Woolwich design of Mk III.
RML 7 inch 7 ton gun
RML 7 inch 6½ ton gun
This was a naval gun introduced in 1865 "...as a broadside or pivot gun for frigates, to replace the 7-inch B.L. and 68-pr S.B. guns, and is now very extensively used, 331 having been made... These guns are in total length 18 inches shorter than the land service [i.e. 7-ton] 7-inch gun, being a length more suited to the requirements of the Navy".The following warships were armed with the gun :s in commission from 1865
- HMS BellerophonHMS Bellerophon (1865)HMS Bellerophon was a central battery ironclad built for the Royal Navy in the mid-1860s.-Design and description:In this ship, designed by Sir Edward Reed, the power-to-weight ratio was increased; the long rows of guns on the broadside were replaced by a small number of guns, centrally placed, of...
commissioned in 1866 - HMS Vixen commissioned 1866
- HMS ViperHMS Viper (1865)HMS Viper was an armoured iron gunboat, the only ship of her class, and the fourteenth ship of the Royal Navy to bear the name.-Design:...
commissioned 1866s commissioned 1867s in commission from 1867s (as re-gunned in 1867) - HMS EnterpriseHMS Enterprise (1864)The seventh HMS Enterprise of the Royal Navy was an armoured sloop launched in 1864 at Deptford Dockyard. Originally laid down as a wooden screw sloop of the Camelion class, she was redesigned by Edward Reed and completed as a central battery ironclad...
& (as re-gunned in 1868)s (as re-gunned in 1867-1868)s (from 1868) - HMS AchillesHMS Achilles (1863)The broadside ironclad HMS Achilles was the third member of the 1861 programme, was described as an armoured frigate, and was originally projected as a modified version of the earlier ....
(as re-gunned in 1868) - HMS InconstantHMS Inconstant (1868)HMS Inconstant was an iron screw frigate of the Royal Navy. She was launched on 12 November 1868 and became a training ship in 1906, renamed Impregnable II. She became the Navy's torpedo school ship in January 1922 and was renamed Defiance IV, and Defiance II in December 1930, before being finally...
in commission from 1869 - HMS ShahHMS Shah (1873)The first HMS Shah was a 19th century unarmoured iron hulled, wooden sheathed frigate of Britain's Royal Navy designed by Sir Edward Reed. She was originally to be named HMS Blonde but was renamed following the visit of the Shah of Persia in 1873....
in commission from 1876
RML 7 inch 90 cwt gun
This was a lighter (90 cwt = 4½ tonsLong ton
Long ton is the name for the unit called the "ton" in the avoirdupois or Imperial system of measurements, as used in the United Kingdom and several other Commonwealth countries. It has been mostly replaced by the tonne, and in the United States by the short ton...
) low-powered naval gun introduced in 1874 as a broadside gun on unarmoured vessels, and not intended for attacking armour plate. Early models were made by simply turning off some of the jacket around 7-inch 6½ ton guns, as firing with reduced charges placed less strain on the coils. Some new guns were made to similar design.
The following warships were armed with the gun :s in commission from 1874
- HMS Raleigh in commission from 1874s in commission from 1874s in commission from 1877s in commission from 1877
Ammunition
The primary projectile for 7 ton and 6½ ton guns was Palliser shot or shellPalliser shot
Palliser shot was invented by Sir William Palliser and hence its name. It was an early British armour-piercing artillery projectile, intended to pierce the armour protection of warships being developed in the second half of the 19th century.-History:...
for attacking armoured warships, fired with a large "battering" charge for maximum velocity. All guns were also equipped with shrapnel shells for anti-personnel use and explosive common shells for attacking unarmoured targets. The "double" common shell was much longer than the standard common shell, and hence contained approximately twice as much gunpowder. It was unstable in flight and hence inaccurate beyond 2,000 yards but was considered useful for attacking wooden warships at ranges below 2,000 yards.
Surviving examples
- Restored 6½ ton Mk I Numbers 148 & 163 at Garden Island Rockingham, Western Australia (Fleet Base West). For restoration story see http://www.defence.gov.au/news/navynews/editions/4719/feature/feature06.htm
- Several 6½ ton Mk I guns on Ascension Island
- 6½ ton Mk I at Fort SilosoFort SilosoFort Siloso is the sole restored coastal gun battery from the twelve such batteries which made up "Fortress Singapore" at the start of World War II...
, Singapore - 6½ ton Mk III of 1869, at Elizabeth Castle, Jersey, UK
- Remains of several 7 ton Mk III guns on Flat HolmFlat HolmFlat Holm is a limestone island lying in the Bristol Channel approximately from Lavernock Point in the Vale of Glamorgan, but in the City and County of Cardiff. It includes the most southerly point of Wales....
island, UK - A 7-ton Mk I gun at The Citadel, Nova Scotia, Canada
