Military Wiki
Ordnance RBL 40 pounder gun
RBL 40 pounder Tasmania 1902 AWM A04785 clipped 300px.jpeg
Launceston Volunteer Artillery, Tasmania, 1902
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)[2]

The Armstrong RBL 40 pounder gun was an early attempt to use William Armstrong's new and innovative breechloading mechanism for medium artillery.

Design history

35 cwt barrel dimensions

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.[3]

The first version weighed 32 cwt, followed by the 35 cwt version which introduced a longer and stronger breech-piece.[4]


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 It was withdrawn from service by 1877.[5]

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.[6] They differed from the wedge guns in that the vent piece was still locked in place by tightening the screw behind it.

Naval service

35 cwt broadside gun on HMS Warrior

The gun was recommended in 1859 for the Navy as a broadside or pivot gun.[4]

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

The 40-pounder we found answer exceedingly well, for coming out of the place [Kagoshima] we planted common shell, with pillar fuze, wherever we wished, at a range of 3,800 yards. Three steel vent-pieces broke, but another placed them immediately and no harm was done. These guns work very easily, are very true, and the drill is very simple.

—Reported in The Times, 25 April 1864.[7]

Land service

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

British Service

The guns were typically employed mounted on high "siege travelling carriages" for use as semi-mobile guns in forts, firing over parapets. Many were mounted on travelling carriages and used by many 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.

Colony of Victoria service

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.[8]

Colony of Tasmania service

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,[9] which they continued to operate until at least 1902.

Surviving examples

See also

Notes and references

  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. 2.0 2.1 2.2 2.3 2.4 Text Book of Gunnery, 1887 Cite error: Invalid <ref> tag; name "Gunnery1887" defined multiple times with different content
  3. Ruffell, The Armstrong Gun Part 5: British revert to Muzzle Loading
  4. 4.0 4.1 Treatise on Manufacture of Service Ordnance, 1877
  5. Treatise on Manufacture of Service Ordnance, 1877. pages 89, 153
  7. The Times, 25th April 1864 : 25 April 1864 THE ARMSTRONG GUNS IN JAPAN
  8. Friends of the Cerberus Website : slideshow
  9. 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

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