RBL 40 pounder Armstrong gun

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Ordnance RBL 40 pounder gun
RBL 40 pounder 35 cwt gun diagram.jpg
Diagram from 'Treatise on Service Ordnance' (HMSO), 1877
Type Naval gun
Fortification gun
Place of origin United Kingdom
Service history
In service 1860s - 1900?
Used by  United Kingdom
Australian colonies
Wars New Zealand Land Wars
Bombardment of Kagoshima
Production history
Designer W.G. Armstrong Co.
Manufacturer W.G. Armstrong Co.
Royal Gun Factory
Produced 1859 - 1863
Number built 1013[1]
Variants 32cwt, 35cwt
Weight 32 cwt (3,584 pounds (1,626 kg)), later 35 cwt (3,920 pounds (1,780 kg)) gun & breech[2]
Barrel length 106.3 inches (2.700 m) bore & chamber[2]

Shell 40 pounds 2 ounces (18.20 kg)[2]
Calibre 4.75-inch (120.6 mm)[2]
Breech Armstrong screw with vertical sliding vent-piece (block)
Muzzle velocity 1,180 feet per second (360 m/s)[3]

The Armstrong RBL 40 pounder gun was introduced into use in 1860 for service on both land and sea. It used William Armstrong's new and innovative breechloading mechanism. It remained in use until 1902 when replaced by more modern Breech Loading (BL) guns.

Design history[edit]

The Armstrong "screw" breech had already proved successful in the RBL 12 pounder 8 cwt field gun, and the British Government requested it be implemented for heavier guns despite Armstrong's protests that the mechanism was unsuited to heavy guns.[4] Guns were produced at both the Royal Gun Factory in Woolwich, and the Elswick Ordnance Company.

Like other early Armstrong guns they were rifled on a polygroove system, firing a variety of lead coated projectiles.


The first version weighed 32 cwt, followed by the 35 cwt version which introduced a longer and stronger breech-piece.[5] A 32 cwt variant having a horizontal sliding wedge breech instead of the Armstrong screw with vertical vent-piece was introduced in 1864 as an attempt to address the perceived weaknesses of the screw-breech design. It was withdrawn from service by 1877.[6]

Diagram depicting side-closing version on siege travelling carriage in position to fire over parapet

From 1880 a small number of 35 cwt guns had their trunnion rings rotated to the left to allow the vent-piece to open horizontally to the right, being known as "side-closing" guns.[7] They differed from the wedge guns in that the vent piece was still locked in place by tightening the screw behind it.

Naval service[edit]

35 cwt broadside gun on HMS Warrior

The gun was recommended in 1859 for the Navy as a broadside or pivot gun.[5]

An officer from HMS Euryalus described the gun's performance at the Bombardment of Kagoshima of August 1863:

Land service[edit]

RBL 40-pounder Armstrong gun block trail carriage diagrams

A number of different carriages for guns employed for Land Service were available. A wooden siege carriage with wheels and attached limbers, enabled the guns to be drawn by teams of heavy horses.

For guns mounted in fortifications they could be mounted on two different types of carriage. The first was an iron traversing carriage, enabling the gun to be traversed right and left, with recoil being absorbed with a carriage being mounted on a slide. Others were mounted on high "siege travelling carriages" for use as semi-mobile guns in forts, firing over parapets.

A number were used by many British Volunteer Artillery Batteries to whom they were issued after 1889. Most remained in use in this role until 1902. A number were used for some years afterwards as saluting guns.

Indian subcontinent[edit]

Titled "Dignity & Impudence" for stereotypic personality traits of elephants and mules respectively, this photograph by John Burke shows an elephant and mule battery during the Second Anglo-Afghan War. The mule team would have hauled supplies or towed the small field gun, while the elephants towed the larger gun. The gun appears to be an rifled muzzle loader (RML) 7-pounder mountain gun. The men in the photograph are a mix of British soldiers and Indian sepoys. The group kneeling around the smaller, muzzle-loaded field gun is preparing to fire after the soldier at front left has used the ramrod to jam the charge down into the gun. The gun at right, towed by elephants, appears to be an rifled breech loader (RBL) 40-pounder Armstrong.[9]

An RBL 40-pounder Armstrong breechloader appears to be present in a photograph by John Burke (photographer) from the Second Anglo-Afghan War (November 1878 - September 1880). The war began when Great Britain, fearful of what it saw as growing Russian influence in Afghanistan, invaded the country from British India. The first phase of the war ended in May 1879 with the Treaty of Gandamak, which permitted the Afghans to maintain internal sovereignty but forced them to cede control over their foreign policy to the British. Fighting resumed in September 1879, after an anti-British uprising in Kabul, and finally concluded in September 1880 with the decisive Battle of Kandahar.[9]

Colony of Victoria service[edit]

The Australian colony of Victoria received six 35 cwt guns in August 1865. They were used as mobile coast fortification guns with one gun being fitted to the colonial sloop Victoria during 1866 & 1867. Later four of the guns were used as field guns at Hastings. Three of these guns are known to survive.[10]

Colony of Tasmania service[edit]

40 pounder RBL, Launceston Volunteer Artillery, Tasmania 1902

As a result of the Jervois-Scratchley reports of 1877 into the defence of Australian colonies following the withdrawal of British troops, the Launceston Volunteer Artillery Corps in Tasmania acquired 2 guns on late-model iron carriages with iron wheels,[11] which they continued to operate until at least 1902.

Surviving examples[edit]

See also[edit]

Notes and references[edit]

  1. ^ 1013 were in service in 1877 : 819 35cwt & 194 32cwt. Quoted in Treatise on Manufacture of Ordnance 1877, page 150. Holley 1865, page 13 quotes 641 as at 1863 : 535 manufactured by Elswick Ordnance and 106 by the Royal Gun Factory. From the Report of the Select Committee on Ordnance, 1863.
  2. ^ a b c d Text Book of Gunnery, 1887
  3. ^ 1180 ft/sec firing 40 lb 2 oz projectile with 5 lb RLG2 (gunpowder). Text Book of Gunnery 1887, Table XVI page 313
  4. ^ Ruffell, The Armstrong Gun Part 5: British revert to Muzzle Loading
  5. ^ a b Treatise on Manufacture of Service Ordnance, 1877
  6. ^ Treatise on Manufacture of Service Ordnance, 1877. pages 89, 153
  7. ^ http://www.victorianforts.co.uk/art/gun2.htm#rbl
  8. ^ The Times, 25th April 1864 : 25 April 1864 THE ARMSTRONG GUNS IN JAPAN http://www.pdavis.nl/Japan.php
  9. ^ a b Elephant and Mule Battery ("Dignity & Impudence") WDL11496.png caption, Library of Congress
  10. ^ Friends of the Cerberus Website : slideshow http://www.cerberus.com.au/reenactors/40_pounder_slideshow.html
  11. ^ David Spethman, "The Garrison Guns of Australia" page 49. 2008, published by Ron H Mortensen, Inala, Qld. ISBN 978-0-9775990-8-0


External links[edit]