RML 12-inch 35-ton gun

RML 12-inch 35-ton guns were large rifled muzzle-loading guns used as primary armament on British battleships of the 1870s. They were the longer and more powerful of the two 12-inch British RML guns, the other being the 25-ton gun.

Ordnance RML 12-inch 35-ton gun
An interior view of one of the two main battery turrets aboard the British battleship HMS Devastation, showing a rear view of the turret's two 12-inch (305 mm) 35-ton rifled muzzle-loaders. These guns were replaced in 1891 by 10-inch (254 mm) breech-loading rifles.
TypeNaval gun
Service history
In service1873–1909
Used byRoyal Navy
Production history
Designed1871
ManufacturerRoyal Arsenal
Unit cost£2,154[1]
No. built15[2]
Specifications
Mass35 long tons (36,000 kg)
Barrel length162.5 inches (4.13 m) (bore + chamber)[3]
Shell706 pounds 12 ounces (320.6 kg) (Palliser)
613 pounds (278.1 kg) (Common & Shrapnel)
Calibre12-inch (304.8 mm)
Muzzle velocity1,390 feet per second (420 m/s)[4]

Design
Barrel construction

This gun design originated in 1871 as an 11.6-inch (295 mm) gun firing a 700-pound (317.5 kg) projectile. Results were unsatisfactory, leading to the gun being bored out to 12 inches (305 mm) and firing a 706-pound-12-ounce (320.6 kg) shell.[2]

Guns were mounted on :

Note : The two 12-inch guns installed in HMS Thunderer's forward turret were 12.5-inch 38-ton guns bored instead to 12 inches, and designated "12-inch 38-ton", as the necessary 12-inch 35-ton guns were not available. These 2 guns used the same charges and projectiles as the standard 12-inch 35-ton guns installed in Thunderer's aft turret which simplified the supply of ammunition.[5] It was one of these "12-inch 38-ton" guns that was accidentally double-loaded and exploded on 2 January 1879.

Ammunition
  • Studded Palliser, Common and Shrapnel projectiles
  • Studless Palliser, Common and Shrapnel projectiles

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 706-pound "Palliser" armour-piercing shot, which were fired with a "battering charge" of 110 pounds of "P" (gunpowder) for maximum velocity and hence penetrating power. Shrapnel and common (exploding) shells weighed 613 pounds and were fired with a "full charge" of 85 pounds "P" or 67 pounds "R.L.G.".[6]

See also

References
  1. Unit cost of £2,153 13 shillings 9 pence is quoted in "The British Navy" Volume II, 1882, by Sir Thomas Brassey. p. 38
  2. Treatise on Construction of Service Ordnance, 1879, p. 284
  3. Treatise on Construction of Service Ordnance 1877, p. 292
  4. MV of 1,390 feet/second firing 706-pound 12-oz projectile with "Battering charge" of 110 pounds "P2" (gunpowder) is quoted in "Text Book of Gunnery 1887" Table XVI. 110 pounds "P" "Battering charge" is quoted in Treatise on Ammunition 1877, p. 220
  5. Brassey 1882, pp. 81–85
  6. Treatise on Ammunition 1877, pp. 191,194, 220

Bibliography
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