William Armstrong's innovative combination of a rifledbuilt-up gun with breechloading had proven suitable for small cannon. When it was applied to a 7-inch gun, it proved that the pressure caused by the explosive charge that was required to propel a 110-pound shot was too much for his breechloading system.
Description
82 cwt gun construction
Breech mechanism
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, a tube was inserted in the top of the vent-piece, and the gun was fired.
Shells had a thin lead coating which made them fractionally larger than the gun's bore, and which engaged with the gun's rifling grooves to impart spin to the shell. This spin, together with the elimination of windage as a result of the tight fit, enabled the gun to achieve greater range and accuracy than existing smoothbore muzzle-loaders with a smaller powder charge.
On top of each powder cartridge was a "lubricator" consisting of tallow and linseed oil between two tin plates, backed by a felt wad coated with beeswax and finally by millboard. The lubricator followed the shell down the bore, the lubricant was squeezed out between the tin plates and the wad behind it cleaned out any lead deposits left from the shell coating, leaving the bore clean for the next round.[6]
History
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[7]
A fibreglass replica aboard the museum ship HMS Warrior at Portsmouth, United Kingdom. Shells for the gun are on deck in the foreground.
The gun as first made weighed 72 cwt (8,064lb) but the heavier 82 cwt (9,184lb) 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.[8]
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 11lb for the 82 cwt gun and 10lb 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.
—Lieutenant-Colonel C. H. Owen, Royal Artillery, reflecting the establishment opinion in 1873.[9]
Critics also considered that the manual labour needed to raise the heavy (136lb) 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[10]
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.[11]
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 wrought-iron "A" tube surrounded by wrought-iron coils, was considered sound and was retained for the first generation of new rifled muzzle-loaders in the mid-1860s.
When Britain returned to breech-loaders in 1880 it used the Elswick cup and the French De Bange obturation systems, both of which used the power of the gun's firing to achieve obturation rather than manual labour.
Use in action
An Armstrong 7-inch (178mm) rifled breechloader in the 19th century.
The gun was used extensively by Royal Navy ships against land fortifications in the Bombardment of Kagoshima and Bombardment of Shimonoseki in 1863 and 1864. We have two descriptions of the same incident aboard HMSEuryalus at the Bombardment of Kagoshima in August 1863:
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?'
My opinion, and also that of the gunnery lieutenant, is that for long range they [Armstrong guns], are most successful. The 100-pounder (sic) as a pivot gun 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 on 25 April 1864.[13]
The guns, while functioning well when correctly handled, were hence seen to be difficult and potentially dangerous to use under the stress of combat.
During the New Zealand Wars, the gun was used in the bombardment of the Maori fortifications at Gate Pa on 29 April 1864.[14] Although subjected to one of the fiercest bombardments of the wars, the Maori defenders were protected by anti-artillery bunkers and went on to repel the British force, inflicting heavy casualties.[15]
↑ £424/13 shillings Royal Gun Factory (Woolwich) production cost 1859–1862; £650 Elswick Ordnance (Armstrongs) production cost 1862–63. Report of the Select Committee on Ordnance 1862. The gun was not sold commercially, hence a sale price is not available. Quoted in Holley 1865, pages 25–26
↑ 959 were in service in 1877: 883 82cwt & 76 72cwt. Quoted in Treatise on Manufacture of Ordnance 1877, page 150. Holley 1865, page 13 quotes 799 as at 1863: 179 manufactured by Elswick Ordnance and 620 by the Royal Gun Factory. From the Report of the Select Committee on Ordnance, 1863.
1 2 3 1100 ft/sec firing 109 pound projectile with 11lb RLG2 (gunpowder). Text Book of Gunnery 1887, Table XVI page 313
1 2 The gun was originally a "100-pounder". In 1861 the projectile weight was increased to 110-pound and this became standard and was used to describe the gun. In 1865 a "light" shell of 90 lb was adopted for naval service for the 82 cwt gun only, to reduce recoil. The light shell was unsuitable for the 72 cwt gun as its reduced 10 lb charge with the light shell was insufficient to break up and distribute the lubricator in the bore (Treatise on Ammunition 1877, page 153). The gun's later official designation was "7-inch" (Treatise on Manufacture of Ordnance 1877, page 154). 109 lb projectile is given in Text Book of Gunnery, 1887. The 1902 Text Book of Gunnery refers only to a 100 lb shell for both 72 cwt and 82 cwt guns.
A rifled breech loader (RBL) is an artillery piece which, unlike the smoothbore cannon and rifled muzzle loader which preceded it, has rifling in the barrel and is loaded from the breech at the rear of the gun.
Dahlgren guns were muzzle-loading naval gun designed by a United States Navy Rear Admiral John A. Dahlgren, mostly used in the American Civil War. Dahlgren's design philosophy evolved from an accidental explosion in 1849 of a 32 lb (14.5 kg) gun being tested for accuracy, killing a gunner. He believed a safer, more powerful naval cannon could be designed using more scientific design criteria. Dahlgren guns were designed with a smooth curved shape, equalizing strain and concentrating more weight of metal in the gun breech where the greatest pressure of expanding propellant gases needed to be met to keep the gun from bursting. Because of their rounded contours, Dahlgren guns were nicknamed "soda bottles", a shape which became their most identifiable characteristic.
This article explains terms used for the British Armed Forces' ordnance (weapons) and ammunition. The terms may have different meanings depending on its usage in another country's military.
A muzzle-loading rifle is a muzzle-loaded small arm that has a rifled barrel rather than a smoothbore, and is loaded from the muzzle of the barrel rather than the breech. Historically they were developed when rifled barrels were introduced by the 1740ies, which offered higher accuracy than the earlier smoothbores. The American longrifle evolved from the German "Jäger" rifle; a popularly recognizable form of the "muzzleloader" was the Kentucky Rifle. Although by definition they must be reloaded after each shot in a time-consuming fashion, they are still produced for hunting.
An Armstrong gun was a uniquely designed type of rifled breech-loading field and heavy gun designed by Sir William Armstrong and manufactured in England beginning in 1855 by the Elswick Ordnance Company and the Royal Arsenal at Woolwich. Such guns involved a built-up gun construction system of a wrought-iron tube surrounded by a number of wrought-iron strengthening coils shrunk over the inner tube to keep it under compression.
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.
The Ordnance BL 12-pounder 7cwt was the British Army's field gun which succeeded the RML 13-pounder 8 cwt in 1885.
The BL 6-inch gun Marks II, III, IV and VI were the second and subsequent generations of British 6-inch rifled breechloading naval guns, designed by the Royal Gun Factory in the 1880s following the first 6-inch breechloader, the relatively unsuccessful BL 6-inch 80-pounder gun designed by Elswick Ordnance. They were originally designed to use the old gunpowder propellants but from the mid-1890s onwards were adapted to use the new cordite propellant. They were superseded on new warships by the QF 6-inch gun from 1891.
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 rifled breechloading mechanism. It remained in use until 1902 when replaced by more modern Breech Loading (BL) guns.
The Armstrong Breech Loading 20-pounder gun, later known as RBL 20-pounder, was an early modern 3.75-inch rifled breech-loading light gun of 1859.
The RML 9-inch guns Mark I – Mark VI were large rifled muzzle-loading guns of the 1860s used as primary armament on smaller British ironclad battleships and secondary armament on larger battleships, and also ashore for coast defence. It should not be confused with the RML 9-inch Armstrong Gun, used by the Dutch navy, the Spanish Navy, and other navies.
The BL 6-inch 80-pounder gun Mk I was the first generation of British 6-inch breechloading naval gun after it switched from muzzle-loaders in 1880. They were originally designed to use the old gunpowder propellants.
The 68-pounder cannon was an artillery piece designed and used by the British Armed Forces in the mid-19th century. The cannon was a smoothbore muzzle-loading gun manufactured in several weights firing projectiles of 68 lb (31 kg). Colonel William Dundas designed the 112 cwt version in 1841 which was cast the following year. The most common variant, weighing 95 long cwt (4,800 kg), dates from 1846. It entered service with the Royal Artillery and the Royal Navy and saw active service with both arms during the Crimean War. Over 2,000 were made and it gained a reputation as the finest smoothbore cannon ever made.
The RML 7-inch guns were various designs of medium-sized rifled muzzle-loading guns used to arm small to medium-sized British warships in the late 19th century, and some were used ashore for coast defence.
The RML 40-pounder gun was a British rifled muzzle-loading siege and fortification gun designed in 1871. It was intended to supersede the RBL 40-pounder Armstrong gun after the British military reverted to rifled muzzle-loading artillery until a more satisfactory breech-loading system than that of the Armstrong guns was developed.
The ML 8-inch shell guns of 50 cwt, 54 cwt and 65 cwt were the three variants of British cast iron smoothbore muzzle-loading guns designed specifically to fire the new generation of exploding shells pioneered in the early to mid-nineteenth century by Henri-Joseph Paixhans.
The RML 13-pounder 8 cwt gun was a British Rifled, Muzzle Loading (RML) field artillery gun manufactured in England in the 19th century, which fired a projectile weighing approximately 13 pounds (5.9 kg). "8 cwt" refers to the weight of the gun.
The RML 25-pounder gun was a British rifled muzzle-loading light siege gun and gun of position designed in 1871. It was intended to be an intermediate gun between the 16-pounder and 40-pounder Rifled Muzzle Loading guns. It was part of a series of guns designed after the British military reverted to rifled muzzle-loading artillery until a more satisfactory breech-loading system than that of the Armstrong guns was developed.
The RML 9-inch Armstrong Gun was a rifled muzzle loading gun, used in substantial numbers by the Dutch navy, the Spanish Navy, and other navies. It should not be confused with the RML 9-inch 12-ton gun, used in the British Royal Navy.
The RML 7-inch Armstrong Gun was a rifled muzzle loading gun. It was an export version of the British Royal Navy's RML 7-inch gun. The RML 7-inch Armstrong Gun was produced by William Armstrong's Elswick Ordnance Company.
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