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 of Great Britain and Ireland
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
Weight	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)^[1]
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)^[1]

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 incorrectly 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 their basic parts so they could be transported by pack animals (4 mules) or men. The barrel and breech were carried separately, and 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, despite the fact that 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 WWI 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 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 romanticised in Rudyard Kipling's poem "Screw-Guns".

Notes

1 2 3 4 Hall, June 1971
↑ Ruffell
↑ Farndale 1988, page 331-332

References

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

Wikimedia Commons has media related to RML 2.5 inch Mountain Gun.

War Monthly, March 1976, SCREW GUNS

British Empire Small Arms & Ordnance of the Victorian era

Side arms

Muskets and Rifles

Artillery

Field Artillery	SBML 9 pounder 13 cwt RBL 9 pounder RBL 12 pounder RBL 20 pounder RML 9 pounder 8 cwt RML 13 pounder 8 cwt RML 16 pounder 12 cwt BL 12 pounder 7 cwt BL 12 pounder 6 cwt QF 12 pounder 8 cwt BL 15 pounder QF 1 pounder pom-pom

Mountain artillery	RML 7 pounder Mountain Gun RML 2.5 inch Mountain Gun

Howitzers, medium, and heavy artillery	RML 6.3 inch Howitzer RML 6.6 inch howitzer BL 5 inch Howitzer BL 5.4 inch Howitzer

Siege & garrison artillery	SBBL 32 pounder SBML 24 pounder SBML 8 inch 65 cwt RBL 40 pounder RBL 7 inch RML 25 pounder 18 cwt RML 40 pounder gun RML 64 pounder 64 cwt gun RML 64 pounder 58 cwt RML 64 pounder 71 cwt gun RML 80 pounder RML 6.6 inch gun RML 8 inch howitzer BL 5 inch gun Mk I - V BL 6 inch 30 cwt howitzer BL 9.45-inch howitzer

Coastal artillery	QF 4.7 inch BL 6 inch Mk III, IV, VI BL 6 inch Mk V RBL 7 inch RML 7 inch RML 8 inch BL 8 inch Mk VII RML 9 inch BL 9.2 inch Mk IV & VI BL 10 inch Mk I BL 12 inch Mk I, VI, VII RML 12.5 inch RML 16 inch RML 17.72 inch

Mortars

13 inch 36 cwt mortar
10 inch 18 cwt mortar
8 inch 9 cwt mortar

War rockets

Congreve 6-pounder
Congreve 12-pounder
Congreve 24-pounder
Boxer
Hales 9-pounder
Hales 24-pounder

Machine guns

British Empire Small Arms & Ordnance of the First World War

No. 1
No. 2 Hales Pattern
Nos. 3, 20, 24, 35 Hales rifle grenades
Nos. 5, 23, 36 Mills
No. 6
Nos. 8, 9 Jam Tin
No. 13 Battye
No. 14 Pitcher
No. 15 Ball
No. 16 Oval
No. 17 Opera hat
No. 18
No. 19
No. 21 "Spherical"
No. 22 Newton-Pippin
No. 25 Sangster
No. 27
No. 28 Chemical
No. 29 Gas
No. 31 Day Signal
No. 32 Night Signal
No. 32 "Spherical E"
No. 34 Egg
No. 37
No. 39 Steuart Pattern

Artillery

Tank guns	QF 6 pounder Hotchkiss QF 6 pounder 6 cwt

Infantry guns	1.59-inch Breech-Loading Vickers Q.F. Gun, Mk II ("Vickers-Crayford rocket gun")

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

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

Howitzers, medium, and 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

Coastal artillery	QF 4 inch naval gun Mk I – III BL 6 inch Mk VII naval gun BL 9.2 inch gun Mk IX–X RML 9 inch

Mortars

Grenade launchers

Smoke and chemical weapons

Railway guns

Anti-aircraft guns

Foreign weapon designs
in British Empire Armies use

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