RBL 12 pounder 8 cwt Armstrong gun

Infobox Weapon
name=RBL 12 pounder 8 cwt gun


caption=At the Australian War Memorial, Canberra
origin=flagcountry|United Kingdom
type=Field gun
is_ranged=yes
is_artillery=yes
is_UK=yes
service=1859 - 19??
used_by=British Empire
wars=New Zealand Land Wars
American Civil War
designer=W.G. Armstrong Co.
design_date=
manufacturer=
unit_cost=
production_date=
number=
variants=
weight=
length=
part_length=First model : total 84 inch, bore 73.375 inch
New model : total 72 inch, bore 61.375 inch (20.46 calibres)Text Book of Gunnery 1902, Page 336]
width=
height=
crew=
caliber=convert|3|in|sigfig=3|sing=on
cartridge=10 lb 11 oz Shrapnel
11 lb 4 oz common shell
11 lb 8 oz Segment
10 lb 9 oz case
rate=
velocity=convert|1239|ft/s|m/s
range=convert|3400|yd|m
feed=
sights=
breech=
recoil=
carriage=
elevation=
traverse=The Armstrong Breech Loading 12 pounder 8 cwt, later known as RBL 12 pounder 8 cwt, was an early modern 3-inch rifled breech-loading field gun of 1859.

History

The gun incorporated some advanced features for its day. It was one of the first breech-loaders : shell and gunpowder propellant were loaded through the gunner's end of the barrel, rather than through the muzzle as in previous guns, allowing a higher rate of fire. The shells were coated with lead, which engaged spiral grooves cut inside the barrel ("rifling") and caused the shell to spin rapidly in flight and hence imparted far greater accuracy and range than previous guns. The lead coating effectively sealed the gap between shell and barrel and eliminated the wastage of propellant gases, previously known as "windage", and hence only half the amount of gunpowder propellant as previous was required.

The barrel was of wrought iron, "built up" of a tube with additional layers heated and then shrunk over it as they cooled. The result was a "pre-stressed" barrel : the interior of the barrel was under compression from the layers shrunk over it, so that the heat and pressure of firing did not stretch it. Hence the barrel was smaller and lighter than previous guns.

The barrel incorporated a slight narrowing with no rifling near the muzzle, to better centre the shell as it left the barrel and to smooth the lead coating. This further improved the shell's ballistic characteristics and hence accuracy and range. This device was omitted from the "New pattern" 24-calibres gun, and did not re-appear until World War II as the "squeeze bore" principle.

United Kingdom service

The gun was the British army's first rifled breechloading field gun, superseding the SBML 9 pounder 13 cwt in 1859.

The gun as originally adopted had a barrel 84 inches long, with a bore of 61.375 inches. The Royal Navy adopted a version with a 72 inch barrel by simply cutting 12 inches off the end, and this version became the general issue.

Unfortunately, the new technology involved required higher standards of gun maintenance and gunner training than the British army was prepared to invest in it, with the result that in service the gun had a reputation for unreliability. In 1871 Britain reverted to muzzle-loading guns, which were cheaper and fired much cheaper ammunition, with the RML 9 pounder 8 cwt.

New Zealand Land Wars

"C" Battery, 4th Brigade Royal Artillery, with 6 guns served in New Zealand under Captain Mercer, in March 1861 in the final stages of the First Taranaki War. Captain Mercer again led this battery in 1863 in the Second Taranaki War until killed. In January 1864 "I" battery, equipped with the "New pattern" of 24-calibres, arrived in New Zealand with another 6 guns.

The guns from Victoria were employed from January 1864 onwards to reinforce "C" and "I" batteries.

These guns appear to have been left in Zealand at the end of the war, and used to equip New Zealand's own militia.

Colony of Victoria service

The Colony of Victoria (today the State of Victoria, in Australia) purchased 6 guns in 1864 to equip its horse artillery; one of these is restored and displayed at the Australian War Memorial in Canberra. [Australian War Memorial. http://cas.awm.gov.au search for REL30087. Accessed 30 August 2008]

The Victorian Government is known to have sold 6 Armstrong 12-pounders to New Zealand for use in the Maori wars, for a sum of 3,592 pounds 1s 8d with equipment and ammunition. [ [http://www.thefreelibrary.com/Australia's+logistical+and+commissariat+support+in+the+New+Zealand...-a0158681391 Military Historical Society of Australia 2006 : "Australia's logistical and commissariat support in the New Zealand wars, 1863-66"] ] They travelled from Melbourne on 7 November 1863 on the troopship Himalaya, and arrived in Auckland on 11 November 1863.

New Zealand Service

See also

*List of artillery#Towed field guns and howitzers

urviving examples

* [http://www.awm.gov.au Australian War Memorial, Canberra]
*Municipal Museum, Roche Street, Te Awamutu, New Zealand

Notes

References

* [http://cgsc.cdmhost.com/u?/p4013coll11,230 Text Book of Gunnery, 1902. LONDON : PRINTED FOR HIS MAJESTY'S STATIONERY OFFICE, BY HARRISON AND SONS, ST. MARTIN'S LANE]
* W.L. Ruffell, [http://riv.co.nz/rnza/hist/arm/arm2.htm The RBL Armstrong 12-pr Field Gun]
* W.L. Ruffell, [http://riv.co.nz/rnza/hist/arm/arm5.htm The Armstrong Gun. Part 5: British revert to Muzzle Loading]
*Major Darrell D. Hall, [http://rapidttp.com/milhist/vol024dh.html "Field Artillery of the British Army 1860-1960. Part I, 1860 - 1900" in The South African Military History Society. Military History Journal - Vol 2 No 4, December 1972] (web page is incorrectly titled 1900-1914)

External links