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The Armstrong GunPart 1: End of the Smooth-Bore EraModern works on artillery tend to convey the impression that the British Armstrong rifled breech-loading (RBL) gun of the 1860s was merely a passing phase, that it was not a success, and therefore worthy of only the briefest mention. One or two indifferent and often inaccurate drawings might be printed but rarely a photograph. Even more rarely do such publications do justice to the events leading up to its adoption into the services, or to the radical advances in armament engineering it displayed, while the real reasons for the later reversion to muzzle-loaders are conveniently ignored. This article seeks to tell the full story including the important part the Armstrong played in New Zealand military history. The middle of the 19th century saw British artillery units still equipped with the same smooth-bore muzzle-loading guns which saw action at Waterloo. Nor had their performance been improved to any appreciable extent. Hitting power fell off rapidly at ranges over 900 metres, while the poor ballistic shape of round shot, excessive windage (1), and crude sighting gear brought effective ranges down to the 400-700m bracket. Yet the artillery was not thought inadequate; the infantry were satisfied with the support they received, and indeed the guns often dominated the battlefield. The reason for this anomalous situation lay in the appalling inefficiency of the common musket. Optimists put its effective range at 200 yards (183 m), but at this range well trained men firing under perfect conditions at targets of 1.75 x 3.00 metres could manage hits with only about 30% of their rounds! Accuracy was deliberately sacrificed in order to obtain a high rate of fire by loading a loose-fitting ball which would drop down the barrel under its own weight, fouling permitting. When fired the ball bounced its way down the bore in zig-zag fashion, the last bounce at the muzzle deciding its line of flight, which might be high, low, left or right, but seldom in the intended direction. Obviously a rifle which could be loaded in the same way was needed, but rifles then in use had to be loaded by forcing a tight-fitting bullet down the barrel, often with the assistance of a mallet, making the rate of fire unacceptably slow. To make matters worse the bullet frequently became distorted from such treatment, and when this occurred accuracy was little better than that of the musket. A solution appeared in the form of the Delvigne-Mini� bullet, which in loading passed easily down the bore, but on firing expanded to the take rifling. Following successful trials it was decided in 1852 to make the Pattern 1851 Mini� rifled musket a general issue, not only to riflemen but also all infantry and Royal Marine units. As other European countries had already commenced issuing the Mini�, or were about to do so, the Master General of the Ordnance soon came to realise that his smooth-bore artillery could possibly be outranged by infantry. He therefore urged that every effort he made to adopt a system of ordnance utilising the principle embodied in the new rifle if feasible. The success of the Dreyse "needle gun" (2) in the Prussian Army had also stimulated thought on breech loading. Having let it be known that they would look with favour upon a suitable rifled gun loading from either breech or muzzle, the authorities soon found themselves assailed by a number of inventors, each proclaiming the advantages of his system. The Ordnance Select Committee instructed to vet them eventually decided only three merited serious consideration; Lancaster, Whitworth and Armstrong. Lancaster's system patented in 1850 was the first examined. It had already achieved notable success in the small arms field, and during trials in 1852-53 to find a replacement for the Mini� (already obsolescent), his rifle came close to being accepted as the service weapon instead of the Pattern 1853 Enfield. His carbine was eventually adopted by the Royal Sappers and Miners (3), over 7000 being made. The Lancaster featured a bore of oval section with a twist increasing from breech to muzzle. Two very desirable factors were apparent in the design: a minimum of metal needed to be removed from the bore in the "rifling" process, and there were no grooves in which fouling could accumulate. At first sight the system looked straightforward enough so the Committee decided to have a number of existing 8in and 10in smooth-bore muzzle-loading guns converted. They soon found this easier said than done. While manufacture of the elliptical cutters required to "rifle" small arms had presented no great obstacle, production of the same tools in sizes to suit heavy ordnance (4) proved exceedingly difficult with the resources available in those days. Ammunition was also a problem. With small arms the soft lead hollow-based bullets employed did not have to be shaped to fit the bore because the pressure of the propellant gases expanded them up to it. However, iron projectiles for the guns were a different proposition altogether; they had to be of oval section especially shaped. Their manufacture was not easy either, but in due course the job was completed. Guns and ammunition were then despatched to the Crimea for trial under active service conditions. For the unfortunate gunners embroiled in that ill conducted campaign the Lancasters were to provide little inspiration. The guns were less accurate than their smooth-bore counterparts, which was bad enough, but worse was to follow. With disconcerting regularity they began to blow up. On taking a second look at the design the experts realised that the projectiles could not accommodate themselves to the increasing twist of the rifling. They tended to jam in the bore, the cast iron barrels could not stand the stresses generated, and the muzzles blew off. later a few guns rifled with uniform twist and firing modified projectiles fared somewhat better, but the Committee were unimpressed. Lancaster was out of running. Until 1854 Whitworth had shown no interest in either small arms or ordnance, and knew little or nothing about them. In May of that year the Board of Ordnance seeking to improve the performance of the Pattern 1853 Enfield rifle ventured to ask his advice on the design and production of rifle barrels. Having consulted the leading gunmakers to learn as much as he could of the problems involved, he came to the conclusion that no one really understood the theory of rifling nor how to apply it in practice. He therefore offered to investigate the problem scientifically. Over the next three years Whitworth conducted numerous experiments. His most important finding was that the twist of tile Enfield rifling, one turn in 78 inches (198mm), was too slow, i.e. the bullets were insufficiently stabilised in flight. He made certain recommendations on twist and bullet weight which the authorities later adopted. At the same time he submitted what he considered the ideal rifle for military purposes. The bore was of .451-in. (11.46mm) calibre, of hexagonal section (5), with a uniform twist of one turn in 20 inches (508mm). Bullets were also hexagonal, shaped to make a close mechanical fit in the bore which would not satisfactorily handle the service projectiles. He did not (and could not) call this barrel his own invention, for it was almost identical to one previously submitted to Ordnance in 1843 by Sergeant Major Moore, Royal Artillery. The Whitworth rifle, a muzzle-loader, was first tried in competition with the Enfield in April 1857, but although it won convincingly, was not accepted. Excessive wear was said to be the main objection. During the years he spent working on small arms, Whitworth was repeatedly requested by the authorities to give some attention to artillery, and bronze castings of 6, 9, 12 and 24-pounders were supplied to him by the Royal Gun Factory for boring and rifling according to his system. These guns were then subjected to extensive trials by the RGF, and all were favourably reported upon. Indeed the range achieved by the 24-pr so far exceeded expectations that a ricochet landed in the drawing room of a resident thought to be a safe distance from the trial area, fortunately without bodily injury to the lady seated therein! The trials of the various inventors' guns had been going on for a number of years in the leisurely manner typical of Victorian times, but although it had been by now generally agreed that the choice lay between those of Armstrong and Whitworth, no final decision had been made. Then in 1858, prompted by fear of an invasion by the French (who had adopted rifled ordinance in 1856), the Secretary of State for War demanded action, and in order to get it, nominated a Special Committee on Rifled Guns. At this stage Armstrong was "ahead on points". While the Special Committee had only a few rifled muzzle-loading castings from Whitworth to assist them in their choice, they had from Armstrong a complete RBL 12-pr field artillery equipment firing a new type of shell. Moreover its range and accuracy astonished them. So impressed were they by its superiority over the current smooth-bore muzzle-loading 9-pr field gun that they gave no more attention to Whitworth's pieces. Without further ado they accepted the Armstrong, and recommended its immediate introduction for special service in the field. The Committee dismissed the Whitworth gun with the observation that the projectiles were liable to jam in loading (no doubt recalling the Lancaster saga), that the bore required too much washing to remove fouling, and the drift (6) was excessive. They also criticised the ammunition, saying the Whitworth shot ranged differently from the shell, and did not achieve the same degree of accuracy. Coming as it did from a Committee of six, five of whom were artillery officers, such a complaint was little short of astounding. Shot and shell of the same calibre weighed differently, the first was solid, the other an assembly, their shape and steadiness differed, so that they could not possibly perform the same, nor do they today. Yet artillery officers were supposed to receive a scientific training. What Whitworth said about the last criticism is not recorded! However, he did contend that no jamming of projectiles had been reported during the trials, and that he had eliminated washing by using lubricated wads. He also stated he had reduced the drift (7), but his protests were of no avail. The Special Committee, under some pressure from the Secretary of State who was demanding a quick answer, were not inclined to reconsider. Needless to say he was unhappy with the situation, and rightly complained that the Committee had reported in favour of Armstrong's equipment without giving his the full and proper examination he felt he had a right to expect. Furthermore, he had not been invited to attend the trials (where he could have fixed or explained temporary difficulties on the spot) while his rival had. So bitter was Whitworth over the treatment he had received, and so convinced was he that his principle of hexagonal rifling was sound, that he determined to enter the field of armament manufacture himself. He later made a gun which surpassed Armstrong's in range, accuracy and ease of handling. It attracted so much public interest and comment that in 1860 the War Department was moved to authorise new trials. Now Whitworth was really "up against it". The senior member of the Ordnance Select Committee appointed to conduct the trials was chairman of the committee who had accepted the Armstrong gun in 1858. Also it was evident the other members had preconceived views on the subject, and human nature being what it is, it seemed unlikely they would switch to the Whitworth at this stage. Besides, the re-equipping of the forces with Armstrongs was already well under way. There ensued conflict between the parties over the conditions under which the new trials were to take place, and no agreement could be reached. Whitworth finally stated he was prepared to submit his gun to any competent judge, but he had no confidence in the committee. He thereupon declined to proceed with the trials, leaving Armstrong the undisputed victor. In all, the British Government accepted six Armstrong equipments for service in the Army and Navy. Their nature and roles were:
All except the 20-pr saw service in New Zealand. Although Armstrong manufactured large numbers of guns both breech and muzzle-loading, the pieces named above are the ones usually referred to as "Armstrong guns" in accounts of 19th century operations. At first they were termed "breech loading" but later "RBL" to distinguish them from "RML" (rifled muzzle-loading), or from the more modern "BL" (8). Their adoption ended the era of smoothbore artillery. In part II of this article we shall examine one of them in detail. NOTES1. Generally reckoned as the difference between the shot and bore diameters. More correctly it is the difference between the cross-sectional areas. Return 2. Adopted In 1848 it was the first bolt action rifle. The "needle" was the firing pin which pierced the base of the paper cartridge, passed through the powder, and struck a primer situated behind the bullet. The front of the bolt was formed into a hollow cone which fitted over a cone-shaped breech, the combination being intended to confine the propellant gases. It was not very efficient. Return 3. This Corps became the Royal Engineers in 1857. Return 4. "Ordnance" and "artillery equipments" are correct generic terms to use when referring collectively to projectors which use explosive force to propel a projectile in the direction of the enemy, with the exception of small arms. A "piece of ordnance" is the "barrel" of a gun with breech mechanism assembled for firing. The term does not include carriage, mounting, etc. Return 5. This is the conventional description. Actually it was not a true hexagon as the angles were rounded or "radiused". Return 6. The lateral displacement of the projectiles from the plane of departure due to its rotation. In British guns the projectile rotates clockwise (looking at it from the breech), hence drift is to the right. Return 7. Whitworth reduced drift by streamlining his projectiles. An added bonus was an increase in range which he predicted. Return 8. As all guns are now breech loading, in modern terms "BL" refers to the means of obturation, i.e. the prevention of escape of gas over or through the breech mechanism, effected in this case by a composition pad suitably fitted to the breech screw working against a coned seating in the end of the chamber. In a "QF" gun the metal cartridge case provides the means of obturation, the pressure of the propellant gases expanding the case against the walls of the chamber to make a gas-tight fit. Return | ||||||||||||||||||||||||||||