RML 12.5-inch 38-ton gun

Ordnance RML 12.5 inch 38 ton gun
Ordnance RML 12.5 inch 38 ton gun
	File:File:12andahalf inch muzzle loading rifled gun (1875) .jpg Gun at Fort Nelson, Portsmouth, UK
Type	Naval gun; Coast defence gun
Place of origin	United Kingdom
Service history
In service	1868 - 19??
Used by	Royal Navy; Australian Colonies
Wars	Bombardment of Alexandria (1882)
Production history
Designer	M Robert Fraser, Royal Gun Factory
Designed	1868
Manufacturer	Royal Arsenal
Unit cost	£1005 10s.
Variants	Mks I - II
Specifications
Barrel length	145.5 inches (3.70 m) (bore)
Shell	400 to 410 pounds (181.4 to 186.0 kg) Palliser, Common, Shrapnel
Calibre	10-inch (254.0 mm)
Muzzle velocity	1,364 feet per second (416 m/s)
Maximum firing range	6,000 yards (5,500 m)

The RML 10 inch guns Mk I - Mk II were large rifled muzzle-loading guns designed for British battleships and monitors.

Design

The 10-inch gun was a standard "Woolwich" 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 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.^[4]

The gun was rifled with 7 grooves, increasing from 1 turn in 100 calibres to 1 in 40.^[2]

It was first used for the main armament on the central battery ironclad HMS Hercules, completed in late 1868.

Ammunition

When the gun was first introduced in 1868, projectiles had several rows of projecting "studs" which engaged with the gun's rifling to impart spin. From the mid-late 1870s, spin was imparted by "gas checks" connected to the base of the projectile which engaged the rifling grooves, making studs unnecessary, and hence the shells were designated "studless".

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^[5] 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^[5], as for these velocity was not as important.


Studless Palliser shell, 410 lb, 1886	Studless Common shell, 410 lb, 1886	Studless Shrapnel shell, 410 lb, 1886

Surviving examples

Damaged Mk I gun No. 17 from HMVS Cerberus is on display at HMAS Cerberus, Victoria, Australia
Mk II gun No. 67 at Southport Gates, Gibraltar
A Mk II gun at Parsons Lodge Battery, Gibraltar
Mk II No. 273 at Almeda Gardens, Gibraltar
Several guns at Fort St Catherine, St George's Island, Bermuda
At the Citadel, Quebec City, Canada

Notes

^ Unit cost of £1005 10 shillings 2 pence is quoted in "The British Navy" Volume II, 1882, by Sir Thomas Brassey. Page 38
^ ^a ^b Treatise on Construction of Service Ordnance 1877, page 292
^ 1,364 feet/second firing 400-pound projectile with "Battering charge" of 70 pound "P" mixture" (gunpowder). Treatise on Construction of Service Ordnance 1877, page 348
^ Treatise on Construction of Service Ordnance 1877, page 92-93
^ ^a ^b Treatise on Ammunition 1877, page 220

References

External links

[1] Unit cost of £1005 10 shillings 2 pence is quoted in "The British Navy" Volume II, 1882, by Sir Thomas Brassey. Page 38

[TOA1877page292-2] Treatise on Construction of Service Ordnance 1877, page 292

[3] 1,364 feet/second firing 400-pound projectile with "Battering charge" of 70 pound "P" mixture" (gunpowder). Treatise on Construction of Service Ordnance 1877, page 348

[4] Treatise on Construction of Service Ordnance 1877, page 92-93

[TOA1877page220-5] Treatise on Ammunition 1877, page 220

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v t e British Empire naval weapons of the Victorian era
Smoothbore muzzle-loading cannons	18-pounder 24-pounder 32-pounder 55 cwt 32-pounder gun 68-pounder Somerset cannon
Smoothbore muzzle-loading shell guns	8-inch 10-inch 86 cwt
Mortars	10-inch Blomefield 13-inch Blomefield
Howitzers	12-pounder Millar 24-pounder Millar
Rifled breechloaders (Armstrong)	RBL 9 pounder RBL 20-pounder RBL 40-pounder RBL 7-inch 110-pounder
Rifled muzzle-loaders (Lancaster)	68-pounder Lancaster gun
Rifled muzzle-loaders (converted)	RML 64-pounder 71 cwt
Rifled muzzle-loaders (Woolwich)	RML 9-pounder 8 cwt RML 64-pounder 64 cwt RML 7-inch RML 8-inch RML 9-inch RML 10-inch RML 11-inch RML 12-inch 25-ton RML 12-inch 35-ton RML 12.5-inch RML 16-inch
Breech-loaders (new pattern)	BL 4-inch BL 5-inch BL 6-inch 80-pounder BL 6-inch Mk II – VI BL 8-inch BL 9.2-inch Mk I – VII BL 9.2-inch Mk VIII BL 10-inch BL 12-inch Mk I – VII BL 12-inch Mk VIII BL 13.5-inch BL 16.25-inch
Quick-firing guns	QF 3-pounder Hotchkiss QF 6-pounder Hotchkiss QF 6-pounder Nordenfelt QF 12-pounder 12 cwt Mk I QF 4-inch QF 4.7-inch QF 6-inch
Light weapons	Gatling gun Gardner gun Nordenfelt gun 1-inch Nordenfelt gun
Torpedoes	Whitehead torpedo