RML 2.5-inch mountain gun

Ordnance RML 2.5-inch mountain gun
Ordnance RML 2.5-inch mountain gun
	Sikh gunners assembling the gun, circa. 1895
Type	Mountain gun
Place of origin	United Kingdom
Service history
In service	1879–1916
Used by	British Empire; British Raj
Wars	Second Boer War; World War I
Production history
Designer	Colonel le Mesurier, RA
Designed	1877
Manufacturer	Royal Gun Factory
Specifications
Mass	800 pounds (363 kg) total
Length	69 inches (1,750 mm)
Barrel length	66 inches (1,680 mm)
Shell	7 pounds 6 ounces (3.35 kg) (Shrapnel); 8 pounds 2 ounces (3.69 kg) (Ring)
Calibre	2.5 inches (63.5 mm)
Action	RML
Muzzle velocity	1,436 feet per second (438 m/s)
Maximum firing range	3,300 yards (3,018 m); (shrapnel); 4,000 yards (3,658 m); (ring)

The Ordnance RML 2.5-inch mountain gun was a British rifled muzzle-loading mountain gun of the late 19th century designed to be broken down into four loads for carrying by man or mule. It was primarily used by the Indian Army.

History[]

On display at Royal Artillery Museum London.

It was intended as a more powerful successor to the RML 7-pounder Mountain Gun.^[1] Some writers refer to the 2.5-inch gun as a "7-pounder" because it also fired a shell of approximately 7 pounds, but its official nomenclature was 2.5-inch RML.

In 1877 Colonel Frederick Le Mesurier of the Royal Artillery proposed a gun in 2 parts which would be screwed together. The Elswick Ordnance Company made 12 Mk I guns based on his design and they were trialled in Afghanistan in 1879. Trials were successful and Mk II with some internal differences made by the Royal Gun Factory entered service.^[2]

The gun was a rifled muzzle-loader. Gun and carriage were designed to be broken down into 4 parts (barrel, breech, 2 wheels) so they could be transported by pack animals (2 mules each: each mule with a left load and a right load, which must balance) or men. The barrel and breech were screwed together for action, hence the name "screw gun".

Second Boer War[]

Siege of Kimberley, 1899–1900

Sikh gunners with a "screw gun"

The gun was used in the Second Boer War (1899–1902) on its standard mountain gun carriage, and also with the Natal Field Battery at Elandslaagte and Diamond Fields Artillery at Kimberley on field carriages which had larger wheels and gave greater mobility.^[1]

A major defect in the war was that the gun's cartridges still used gunpowder as a propellant, although smokeless cordite had been introduced in 1892. The gunpowder generated a white cloud on firing, and as the gun could only be aimed using direct line of sight, this made the gunners easy targets for Boer marksmen as the gun lacked a shield.

It proved to be ineffectual and outclassed by Boer ordnance and was replaced by the BL 10-pounder Mountain Gun from 1901.

World War I[]

Either 4 or 6 guns (sources appear imprecise) were returned to service from Southern African garrisons in 1916 and were employed by the Nyasaland-Rhodesian Field Force in the campaign in German East Africa.^[3] Writers who refer to "7-pounders" in World War I are in fact referring to this 2.5-inch (64 mm) gun.

Surviving examples[]

At Fort Klapperkop, Pretoria

Restored gun is displayed at Firepower, the Royal Artillery Museum. Woolwich London
Two guns are displayed at Fort Charles, Port Royal, Jamaica
Two 2.5-inch (64 mm) RMLs on Field carriages and one on a Mountain carriage, at Fort Klapperkop Military Museum, Pretoria, South Africa.

In literature[]

It was actively described in Rudyard Kipling's poem "Screw-Guns".

Notes and references[]

^ ^a ^b ^c ^d Hall, June 1971
^ Ruffell
^ Farndale 1988, page 331-332

Bibliography[]

General Sir Martin Farndale, "History of the Royal Regiment of Artillery. The Forgotten Fronts and the Home Base, 1914-18". London : The Royal Artillery Institution, 1988 ISBN 1-870114-05-1
Major Darrell D Hall, "Guns in South Africa 1899-1902" in The South African Military History Society Military History Journal – Vol 2 No 1, June 1971
W. L. Ruffell, The Screw Gun

External links[]

Handbook for 2.5-inch R.M.L. steel, jointed, gun mule and camel equipment, 1888 at State Library of Victoria

[HallJune1971-1] Hall, June 1971

[2] Ruffell

[3] Farndale 1988, page 331-332

[1]

[2]

[3]

v t British Empire artillery of the First World War
Armoured vehicle guns	QF 3-pounder Vickers QF 6-pounder Hotchkiss QF 6-pounder 6 cwt
Infantry guns	1.59-inch Breech-Loading Vickers Q.F. Gun, Mk II
Field artillery	BL 12-pounder 6 cwt QF 12-pounder 8 cwt QF 12-pounder 18 cwt QF 13-pounder BL 15-pounder BLC 15-pounder QF 15-pounder QF 18-pounder QF 4-inch gun Mk III BL 4-inch gun Mk VII QF 4.5-inch howitzer
Medium & heavy artillery	QF 4.7-inch gun BL 5-inch howitzer BL 5.4-inch howitzer BL 60-pounder gun BLC 6-inch siege gun BL 6-inch gun Mk VII BL 6-inch gun Mk XIX BL 6-inch 26 cwt howitzer BL 6-inch 30 cwt howitzer BL 8-inch howitzer Mk I – V BL 8-inch howitzer Mk VI – VIII
Siege artillery	BL 7.5-inch Mk III naval gun BL 9.2-inch howitzer BL 9.2-inch Mk X naval gun BL 12-inch howitzer BL 12-inch Mk X naval gun BL 15-inch howitzer
Mountain artillery	RML 2.5-inch mountain gun BL 10-pounder mountain gun BL 2.75-inch mountain gun QF 2.95-inch mountain gun QF 3.7-inch mountain howitzer
Mortars	Garland trench mortar 3-inch Stokes mortar Vickers 1.57-inch mortar 2-inch medium mortar Newton 6-inch mortar 9.45-inch Heavy Mortar
Smoke and chemical weapons	4-inch Stokes Mortar Livens Projector Livens Large Gallery Flame Projector
Anti-aircraft guns	QF 1-pounder pom-pom QF 2-pounder "pom-pom" Mk II 75 mm AA gun QF 12-pounder 12 cwt QF 13-pounder 6 cwt QF 13-pounder Mk IV QF 13-pounder 9 cwt QF 3-inch 20 cwt QF 18-pounder QF 4-inch Mk V
Coastal artillery	QF 12-pounder 12 cwt QF 4-inch naval gun Mk I – III BL 6-inch Mk VII naval gun BL 9.2-inch Mk IX – X naval gun RML 9-inch
Railway guns	BL 9.2-inch railway gun BL 12-inch railway gun BL 12-inch railway howitzer BL 14-inch railway gun