Description
The Armstrong "screw" breech mechanism used a heavy block inserted in a vertical slot in the barrel behind the chamber, with a large hollow screw behind it which was manually screwed tight against the block after loading. A metal cup on the front of the block, together with the pressure of the screw behind it, provided "obturation" and sealed the breech to prevent escape of gasses rearward on firing. The sliding-block was known as the "vent-piece", as the vent tube was inserted through it to fire the gun. In modern terms it was a vertical sliding-block. To load the gun, the vent-piece was raised, the shell was inserted through the hollow screw and rammed home into the bore, and the powder cartridge was likewise inserted through the screw into the chamber. The vent-piece was lowered, the screw was tightened, aHistory
This method had already proved successful in the much smaller RBL 12 pounder 8 cwt field gun, and the British Government requested it be implemented for heavy guns despite Armstrong's protests that the mechanism was unsuited to heavy guns:"The threatening aspects of the continent required that large rifled guns should be procured for naval and siege purposes. I was therefore called upon to produce 40-pounders and 100-pounders without having had an opportunity of testing the patterns by previous trials, though I had stated in my original report that I apprehended that the application of breech-loading to large guns would involve an application of parts which would be inconveniently heavy to handle... I was at first in hopes that the same material which had been used and found to be sufficient for the 40-pounder, would be found equally suitable for the 100-pounder; but that turns out not to be the case. The vent-piece for the 100-pounder continues still to be a difficulty". Sir W Armstrong to the Select Committee on Ordnance in 1863.The gun as first made weighed 72 cwt (8,064 lb) but the heavier 82 cwt (9,184 lb) version, incorporating a strengthening coil over the powder chamber, was the first to enter service in 1861. It was intended to replace the smoothbore muzzle-loading 68-pounder gun, and was intended to be Britain's first modern rifled breech-loading naval gun. The lighter 72 cwt version eventually entered service in 1863 for land use only. The British government's Select Committee on Ordnance held lengthy hearings in 1862 and 1863 on the relative merits of the Armstrong breechloaders compared to other breechloaders and muzzle-loaders. It finally announced:
"... the preponderance of opinion seems to be against any breech-loading systems for the ''larger guns''"It was considered that with a maximum gunpowder propellant charge of only 12 pounds (soon reduced to 11 lb for the 82 cwt gun and 10 lb for the 72 cwt gun) the gun was incapable of a high enough muzzle velocity to penetrate the armour of enemy ships:
"These guns can only be fired with comparatively small charges, and therefore their projectiles would do no injury to ironclad vessels, but their shells would no doubt be most destructive to wooden ships." : the sarcastic comment of Lieutenant-Colonel C H Owen, Royal Artillery, reflecting the establishment opinion in 1873.Critics also considered that the manual labour needed to raise the heavy (136 lb) vent piece out of the breech before reloading was an unnecessary combat impediment. Another objection raised was that obturation (i.e. sealing of the breech on firing) depended on how tightly the gunners turned the breech screw after loading:
"My objection has been to the ''Armstrong'' breech-loader. My objection to that is, that the breech-plug is only a valve; and the first principle of every valve, whether the vessel contain water or oil, or gas, is that the pressure of that fluid should press the valve tighter. Now Sir William Armstrong's breech-loader is on a diametrically opposite system; nothing there confines the gas but the actual amount of labour expended in the screwing up of the breech. If the gas is stronger than the man, aided by the screw, the gas will escape"... Captain Blakely to the Select Committee on Ordnance.As these limitations were imposed by the current Armstrong breechloading design, and as no other suitable breechloading mechanism was available, production of the 110-pounder was discontinued in 1864 and Britain reverted to muzzle-loading heavy guns. The remaining guns were moved to the role of fortress artillery where they remained in post for much of the Victorian era. The abandonment of the Armstrong breech-loading design led Britain to begin a major program of building rifled muzzle-loaders to equip its fleet. The Armstrong 110-pound gun was succeeded by various RML 7 and 8-inch guns. 7-inch Armstrong breech-loaders under construction at the time of cancellation were completed as RML 64-pounder muzzle-loaders. However, the gun construction method developed by Armstrong for breech-loaders, of a
Use in action
The gun was used extensively by Royal Navy ships against land fortifications in the"We had on our main-deck 32-pr. 56 cwt. muzzle-loaders; and they, of course, gave no trouble... in the forecastle we had a 7-in. B.L. 110-pr. Armstrong. Whether the men in the heat of the action became hurried I cannot say; but certain it is that the breech piece of this gun blew out with tremendous effect, the concussion knocking down the whole gun's crew, and apparently paralysing the men, until Webster, captain of the forecastle and of the gun, roused them by shouting: 'Well; is there ere a b----- of you will go and get the spare vent piece?'" -- Letter from an officer of HMS ''Euryalus'' to historianWilliam Laird Clowes Sir William Laird Clowes (1 February 1856 – 14 August 1905) was a British journalist and historian whose principal work was ''The Royal Navy, A History from the Earliest Times to 1900'', a text that is still in print. He also wrote numerous ...many years after the event.
"My opinion, and also that of the gunnery lieutenant, is that for long range they rmstrong guns are most successful. The 100-pounder (sic) as aThe guns, while functioning well when correctly handled, were hence seen to be difficult and potentially dangerous to use under the stress of combat. During thepivot gun A pivot gun was a type of cannon mounted on a fixed central emplacement which permitted it to be moved through a wide horizontal arc. They were a common weapon aboard ships and in land fortifications for several centuries but became obsolete aft ...is superior to the 95 cwt. solid 8-inch gun ; but as broadside guns between decks we do not like them; the smoke is too great. Rear choke carriages with such heavy guns are very slow in working and the decks dreadfully cut up. The common shell is one of its great efficiencies, the bursting charge is so great. At Kagosima one vent-piece of the pivot-gun broke and a piece went up to foreyard, but no one was hurt, and it was the fault of the captain of the gun not putting the tin cap in. If the gun is understood and worked properly, it is very successful". -- An officer from HMS ''Euryalus'', published in ''The Times ''The Times'' is a British daily national newspaper based in London. It began in 1785 under the title ''The Daily Universal Register'', adopting its current name on 1 January 1788. ''The Times'' and its sister paper ''The Sunday Times'' (fou ...'' on 25 April 1864.
Ammunition
Surviving examples
See also
*Notes and references
Bibliography
External links