RML 11-inch 25-ton gun

RML 11-inch 25-ton guns were large 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 instead of 12.

Ordnance RML 11-inch 25-ton gun
Disappearing gun on HMS Temeraire in firing position
TypeNaval gun
Coast defence gun
Service history
In service1867–1903
Used byRoyal Navy
WarsBombardment of Alexandria
Production history
ManufacturerRoyal Arsenal
Unit cost£1,589 (18751)[1]
VariantsMk I, Mk II
Specifications
Mass25 long tons (25,000 kg)
Barrel length145 inches (3.7 m) (bore + chamber)[2]
Shell532 to 543 pounds (241.3 to 246.3 kg) Palliser, Common, Shrapnel
Calibre11-inch (279.4 mm)
Muzzle velocity1,360 feet per second (410 m/s)[3]

Design
Mark I & II gun construction

Mark I was introduced in 1867. Mark II was introduced in 1871 using the simpler and cheaper "Fraser" gun construction method which had proved successful with the RML 9-inch 12-ton Mk IV gun. [4]

In 1874 the process of development made a "New Eighty-one Ton Gun" available in Woolwich.[5]

Guns were mounted on:

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 536–543 lb (243–246 kg) "Palliser" armour-piercing shot, which were fired with a "Battering charge" of 85 lb (39 kg) of "P" (gunpowder) or 70 lb (32 kg) of "R.L.G." (gunpowder) for maximum velocity and hence penetrating power. Shrapnel and Common (exploding) shells weighed 532–536 lb (241–243 kg) and were fired with a "Full charge" of 60 lb (27 kg) "P" or 50 lb (23 kg) "R.L.G.".[6]

See also

Surviving examples
Mk II gun at Fort Nelson, Portsmouth, UK
RML 11-inch 25-ton gun at Fort George in St. George's, Bermuda.

Notes
  2. Treatise on Construction of Service Ordnance 1877, page 292
  3. MV of 1,360 feet/second firing 543-pound 2-oz projectile with "Battering charge" of 85 pounds "P" (gunpowder) is quoted in "Text Book of Gunnery 1887" Table XVI.
  4. Treatise on Construction of Service Ordnance, 1879, page 281-282
  5. Scientific American: Eight-one-ton gun, Mai 30, 1874, page 338 online (archive.org)
  6. Treatise on Ammunition 1877, pages 191,194, 205, 220

References
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