MACHINE-GUN, a weapon designed to deliver a large number of bullets or small shells, either by volleys  or in very quick succession, at a high rate of fire. Formerly the mechanism of machine-guns was hand operated, but all modern weapons are automatic in action, the gas of the explosion or the force of recoil being utilized to lock and unlock the breech mechanism, to load the weapon and to eject the fired cartridge cases. The smaller types approximate to the " automatic rifle," which is expected to replace the magazine rifle as the arm of the infantryman. The large types, generically called " pompoms," fire a light artillery projectile, and are considered by many artillery experts as " the gun of the future." The medium type, which takes the ordinary rifle ammunition but is fired from various forms of carriage, is the ordinary machine-gun of to-day, and the present article deals mainly with this.
 The French term mitrailleuse, made famous by the War of 1870, reappears in other Latin tongues (e.g. Spanish ametraUadora). It signifies a weapon which delivers a shower of small projectiles mitraille grape or case shot), and has no special reference to its mechanical (hand or automatic) action.
HISTORICAL SKETCH Machine-guns of a primitive kind are found in the early history of gunpowder artillery, in the form of a grouping or binding of several small-calibre guns for purposes of a volley or a rapid succession of shots. The earliest field artillery (q.v.) was indeed chiefly designed to serve the purpose of a modern machine-gun, i.e. for a mechanical concentration of musketry. Infantry fire (till the development of the Spanish arquebus, about 1520) was almost ineffective, and the disintegration of the masses of pikes, preparatory to the decisive cavalry charge, had to be effected by guns of one sort or another (see also INFANTRY). Hence the " cart with gonnes," although the prototype of the field gun of to-day was actually a primitive mitrailleuse.
Weapons of this sort were freely employed by the Hussites, who fought in laager formation (Wagenburg), but the fitting of two or more hand-guns or small culverins to a two-wheeled carriage garnished with spikes and scythe blades (like the ancient war-chariots) was somewhat older, for in 1382 the men of Ghent put into the field 200 " chars de canon " and in 1411 the Burgundian army is said to have had 2000 " ribaudequins " ( meaning probably the weapons, not the carts, in this case). These were of course hardly more than carts with hand-gun men; in fact most armies in those days moved about in a hollow square or lozenge of wagons, and it was natural to fill the carts with the available gunners or archers. The method of breaking the enemy's " battles " with these carts was at first, in the ancient manner, to drive into and disorder the hostile ranks with the scythes. But they contained at least the germ of quins. ' tne modern machine-gun, for the tubes (cannes, canons) were connected by a train of powder and fired in volleys. As however field artillery improved (latter half of 15th century), and a cannon-ball could be fired from a mobile carriage, the ribaudequin ceased to exist, its name being transferred to heavy hand-guns used as rampart pieces. The idea of the machinegun reappeared however in the 16th century. The weapons were now called " organs " (argues), from the number of pipes or tubes that they contained. At first used (defensively) in the same way as the ribaudequins, i.e. as an effective addition to the military equipment of a war-cart, they were developed, in the early part of the 16th century, into a really formidable weapon for breaking the masses of the enemy, not by scythes and spikes but by fire. Fleurange's memoirs assign the credit of this to the famous gunner and engineer Pedro Navarro, who made two hundred weapons of a design of his own for Louis XII. These " were not more than two feet long, and fired fifty shots at a round," but nevertheless " organs " were relatively rare in the armies of the 16th century, for the field artillery, though it grew in size and lost in mobility, had discovered the efficacy of case shot (then called " perdreaux ") against uncovered animate targets, and -for work that was not sufficiently serious for the guns heavy arquebuses were employed. Infantry fire, too, was growing in power and importance. In 1551 a French army contained 21 guns and 150 arquebuses a croc and one piece fa^on d'orgue. By about 1 570 it had been found that when an " organ " (<n _ ,. was needed all that was necessary was to mount some urguns. . " heavy arquebuses on a cart, and the organ, as a separate weapon, disappeared from the field, although under the name of " mantelet " (from the shield which protected the gunners), it was still used for the defence of breaches in siege warfare. Diego Ufano, who wrote in the early years of the 17th century, describes it as a weapon consisting of five or six barrels fired simultaneously by a common lock, and mentions as a celebrated example the " Triquetraque of Rome " which had five barrels. Another writer, Hanzelet, describes amongst other devices a mitrailleuse of four barrels which was fired from the back of an ass or pony. But such weapons as these were more curious than useful. For work in the open field the musket came more and more to the front, its bullet became at least as formidable as that of an " organ," and when it was necessary to obtain a concentrated fire on a narrow front arquebuses A croc were mounted for the nonce in groups of four to six. The " organ " maintained a precarious existence, and is described by Montecucculi a century later, and one of twelve barrels figures in the list of military stores at Hesdin in 1680. But its fatal defect was that it was neither powerful enough to engage nor mobile enough to evade the hostile artillery.
Enthusiastic inventors, of course, produced many models of machine-gun in the strict sense of the word i.e. a gun firing many charges, in volleys or in rapid succession, by a mechanical arrangement of the lock. Wilhelm Calthoff, a German employed by Louis XIII., produced arquebuses and muskets that fired six to eight shots per round, but his invention was a secret, and it seems to have been more of a magazine small arm than a machine-gun (1640). In 1701 a Lorrainer, Beaufort de Mirecourt, proposed a machine-gun which had as its purpose the augmentation of infantry-fire power, so as to place an inferior army on an equality with a superior. At this time inventors were so numerous and so embarrassing that the French grand master of artillery, St Hilaire, in 1703 wrote that he would be glad to have done with " ces sortes de gens a secrets," some of whom demanded a grant of compensation even when their experiments had failed. The machine-gun of the 17th and 18th centuries in fact possessed no advantage over contemporary field artillery, and the battalion gun in particular, which possessed the long ranging and battering power that its rival lacked, and was moreover more efficacious against living targets with its case-shot or grape. As compared with infantry fire, too, it was less effective and slower than the muskets of a well-drilled company. Rapid fire was easily arranged, but the rapid loading which would have compensated for other defects was unobtainable in the then existing state of gun-making.
Thus a satisfactory machine-gun was not forthcoming until breech-loading had been, so to speak, rediscovered, that is until about 1860. At that time the tactical conditions of armament were peculiar. As regards artillery, the new (muzzle-loading) longrange rifle sufficed, in the hand of determined infantry, to keep guns out of case-shot range. This made the Napoleonic artillery attack an impossibility. At the same time the infantry rifle was a slow loader, and the augmentation of the volume of infantry fire attracted the attention of several inventors. The French, with their artillery traditions, regarded the machine-gun therefore as a method of restoring the lost superiority of the gunner, while the Americans, equally in accordance with traditions and local circumstances, regarded it as a musketry machine. The representative weapons evolved by each were the canon a holies, more commonly called mitrailleuse, and the Catling gun.
The declared purpose of the canon a holies was to replace the old artillery case-shot attack. Shrapnel, owing to the defects of the time-fuzes then available, had proved disappointing in the Italian War of 1859, and the gun itself, of the existing model, was not considered satisfactory. Napoleon III., a keen student of artillery, maintained a private arsenal and workshop at the chateau of Meudon 1 and in 1866, in the alarm following upon
 Meudon Chateau had long been used for military experiments. The peasantry credited it with mysterious and terrible secrets, asserting even that it contained a tannery of human skins, this tradition perhaps relating to the war balloon constructed there before the battle of Fleurus (1794). Reffye had also many nonmilitary tasks, such as the reproduction of a famous set of bas-reliefs, construction of aeroplanes, and the reconstruction of triremes and balistas.
Koniggriitz, he ordered Commandant Reffye (1821-1880), the artillery officer he had placed in charge of it, to produce a machine-gun. Reffye held that the work of a mitrailleuse should only begin where that of the infantry rifle ceased. The handbook to his gun issued to the French army in 1870 stated that it was " to carry balls to distances that the infantry, and the ThcCaaoa artillery firing case, could not reach." The most "1866 -'IS'TO. su ' ta ble range was given as 1500-2000 yards against infantry in close order, 2000-2700 against artillery. As the French shrapnel (obus d holies) of these days was only used to give its peculiar case-shot effect between 550 and 1350 yards, and even so sparingly and without much confidence in its efficacy, it is clear that the canon d battes was intended to do the field-gun's work, except at (what were then) extreme field artillery ranges (2800 and above), in which case the ordinary gun with common shell (time or percussion) alone was used.
Constructed to meet these conditions, the Reffye machine-gun in its final form resembled outwardly an ordinary field gun, with wheeled carriage, limber and four-horse team. The gun barrel was in reality a casing for 25 rifle barrels disposed around a common axis (the idea of obtaining sweeping effect by disposing the barrels slightly fan-wise had been tried and abandoned). The barrels were held together at intervals by wrought-iron plates. They were entirely open at the breech, a removable false breech containing the firing mechanism (the cartridge cases were of brass, solid-drawn, like those of the American and unlike those of the British Catlings). This false breech, held in the firing position by a strong screw resembling roughly those of contemporary B.L. ordnance such as the Armstrong R. B. L. consisted of a plate with 25 holes, which allowed the points of the strikers to pass through and reach the cartridges. The plate was turned by hand so that one striker was admitted at a time, the metal of the plate holding back the rest. To avoid any deflection of the bullet by the gases at an adjoining muzzle the barrels were fired in an irregular order. Each gun was provided with four chambers, which were loaded with their 25 cartridges apiece by a charger, and fixed to the breech one after the other as quickly as the manipulation of the powerful retaining screw permitted. The rates of fire were " slow, 3 rounds or 75 shots a minute, and " rapid," 5 rounds or 125 shots per minute. One advantage as against artillery that was claimed for the new weapon was rapidity of ranging. Any ordinary target, such as a hostile gun, would, it was expected, be accurately ranged by the mitrailleuse before it was ready to open fire for effect. The ordinary rifle bullet was employed, but to enhance the case-shot effect a heavy bullet made up in three parts, which broke asunder on discharge, was introduced in 1870 in the proportion of one round in nine. The weapon was sighted to 3000 metres (3300 yds.). The initial velocity was 1558 f.s. ; and the weight of the gun 350 kg. (6-45 cwt.), of the carriage 371 kg. (6-86 cwt.); total behind the team, 1,485 kg. (27-1 cwt.).
For an artillery effect, dispersion had to be combined with accuracy. The rifle-barrels when carefully set gave a very close grouping of shots on the target, and dispersion was obtained by traversing the gun during the firing of a round. When this was skilfully performed a front of 18 metres (about 20 yds.) at 1,000 metres range was thoroughly swept by the cone of bullets.
The design and manufacture of these mitrailleuses under the personal orders and at the expense of the emperor enabled the French authorities to keep their new weapon most secret. Even though, after a time, mitrailleuses were constructed by scores, and could therefore no longer be charged to a " sundry " or " petty cash " account in the budget, secrecy was still maintained. The pieces were taken about, muffled in tarpaulins, by by-ways and footpaths. In 1869, two years after the definitive adoption of the weapon, only a few artillery captains were instructed in its mechanism; the non-commissioned officers who had to handle the gun in war were called up for practice in July 1870, when Major Reffye's energies were too much absorbed in turning out the material so urgently demanded to allow him to devote himself to their instruction. The natural consequence was that the mitrailleuses were taken into battle by officers and men of whom nine-tenths had never seen them fire one round of live cartridges. The purpose of this fatal secrecy was the maintenance of prestige. No details were given, but it was confidently announced that war would be revolutionized. One foreign officer only, Major Fosbery, R.A. (see R.U.S.I. Journal, v. xiii.), penetrated the secret, and he felt himself bound in honour to keep it to himself, not even communicating it to the War Office. But public attention was only too fully aroused by these mysterious prophecies. " The mitrailleuse paid dearly for its fame." The Prussians, who had examined mitrailleuses of the Galling or infantry type, were well aware that the artillery machine-gun was at the least a most formidable opponent. They therefore ostentatiously rejected the Galling gun, taught their troops that the new weapons were in the nature of scientific toys, and secretly made up their minds to lurn the whole weight of their guns on to the mitrailleuse whenever and wherever it appeared on the field, and so to overwhelm it at once. This policy they carried inlo effecl in the War of 1870; and although on occasions the new weapon rendered excellent service, in general il cruelly disappointed the over-high hopes of its admirers. And thus, although the Catling and similar types of gun were employed to a slight extent by both sides in the laler stage of the war, machine-guns, as a class of armament for civilized warfare, praclically disappeared.
As a good deal of criticism after the event has been levelled at the French for their " improper use of the machine-gun as a substitute for artillery," it is necessary to give some summary of the ideas and rules which were inspired by the inventor or dictated by the authorities as to its tactical employment. The first principle laid down was that the gun should not be employed within the zone of the infantry fight. Officers commanding batteries were explicitly warned against infantry divisional generals who would certainly attempt to put the batteries, by sections, amongst the infantry. The second principle was that the mitrailleuses were to share the work of the guns, the latter battering obstacles with common shell, and the former being employed against troops in the open, and especially to cover and support the infantry advance. This tendency to classify the r61es of the artillery and to tell off the batteries each in its special task has reappeared in the French, and to a mo -e limited extent in the British, field artillery of to-day (the Germans alone resolutely opposing the idea of subdivision). The mitrailleuse of 1870 was, in fact, intended to do what the perfected Shrapnel of 1910 does, to transfer the case-shot attack to longer ranges. But, as we have seen, secrecy had prevented any general spread of knowledge as to the uses to which the canon A battes was to be put, and consequently, after a few weeks of the war, we find Reffye complaining that the machine-guns were being used by their battery commanders " in a perfectly idiotic fashion. They are only good at a great distance and when used in masses, and they are being employed at close quarters like a rifle." The officers in the field, however, held that it was foolish to pit the mitrailleuse against the gun, which had a longer range, and exerted themselves to use it as an infantry weapon, a concentrated company, for which, unlike the Catlings of 1870 and the machine-guns of to-day, it was never designed. As to which was right in the controversy it is impossible to dogmatize and needless to argue.
Very different was the Galling gun, the invention of Richard Jordan Catling (1818-1903), which came into existence and was to a slight extent used in the field in the latler years of the American Civil War, 1 and also to a still slighler extent by the Bavarians and the French in the latler part of the war of 1870. This was dislinclively an infanlry type weapon, a sort of revolving rifle, the len barrels of which were set around an axis, and fired in turn when brought into position by aatiiag the revolving mechanism. This weapon had a long O""- reign, and was used side by side wilh the lalesl automatic machine gun in the Spanish-American War of 1898. The following account of the old British service Catling (fig. i), as used in the Egyptian and Sudanese campaigns, is condensed from that in the article " Gun-making," Ency. Brit. 9th ed.
A block of ten barrels is secured round an axis, which is fixed in a frame a a. On turning the handle h (fig. 2) the spindle g g causes the worm / to act on the pinion w, making the axis and barrels revolve. A drum T (figs. I and 4) is placed on the top at the breech end of the barrels over a hopper, through a slot in which the cartridges drop into the carrier (fig. 3). The construction of the lock is shown in ng. 4. A A A A is a cam, sloping as in the drawing, which, it must be understood, represents the circular construction opened out and laid flat. As the barrels, carrier and locks revolve the slope of the cam forces the locks forward and backward alternately. At position I. the cartridge has just fallen into the carrier, the lock and bolt are completely withdrawn. At positions II., III., IV., the cam is forcing them forward, so that the bolt pushes the cartridge into the barrel. At IV. the cocking cam R begins to compress the spiral spring, releasing it at V. Position VI. shows the cartridge just after firing ; the extractor is clutching the base of the cartridge 1 A machine-gun of the artillery or volley type, called the " Requa battery," which had its barrels disposed fan-wise, was also used in the Civil War.
case, which is withdrawn as the locks retreat down the slope of the cam, till at X it falls through an aperture to the ground. The drum consists of a number of vertical channels radiating from the centre. The cartridges are arranged horizontally, one above the other, in FIG. i. Catling Gun.
these channels, bullet ends inwards. The drum revolves on the pivot b (fig- 3), and the cartridges fall through the aperture B. When all the channels are emptied, a full drum is brought from the limber, and substituted for the empty one. Each barrel fires in turn as it comes to a certain position, so that by turning the handle quickly an almost continuous stream of bullets can. be ejected.
Experimental Catlings were constructed which could be made to fire nearly 1000 shots a minute, and an automatic traversing arrangement was also fitted.
As has been said, this weapon had a long reign. It was used with great effect in the Zulu War at Ulundi and in the Sudan.
But a grave disadvantage of the English pattern was that it had to be used with the Boxer coiled cartridge supplied for the Martini-Henry rifle, and until this was replaced by a solid-drawn cartridge case it was impossible to avoid frequent " jams." The modern, fully automatic, machine gun suffers from this to a considerable extent,, and it was an even more serious defect with a hand-operated weapon, as the British troops found in their campaigns against the Mahdists. But the Catling had many advantages over its newer rivals as regards simplicity and strength. Theodore Roosevelt, who commanded sections of both types in the Spanish-American War, speaks with enthusiasm of the old-fashioned weapon * while somewhat disparaging the Colt automatic.
The Gardner was another type which had a certain vogue 2 and was used by the British in savage warfare. But, next to In this weapon the barrels are placed horizontally, and have no movement. A box containing the locks, bolts, strikers and spiral springs, one of each corresponding to each barrel, moves Nar ., enlfUt straight backwards and forwards when worked by the \^. handle of the lever on the right. When the box is drawn back the cartridges fall from the holder on the top into the carriers simultaneously. When the box is pushed forward the bolts push the cartridges into the barrel, cocking-catches compress the spiral springs, the lever releases the catches one after the other at very minute intervals of time, and the cartridges are fired in rapid l-io, Parts of frame ; 11, Breech plug; 12, Striker; 13, Extractor; 14, Cartridge receiver; FIG. 5. Nordenfeldt Machine-Gun.
15-18, 23-31, Lock and trigger parts; 19-22, Locking action ; 32-35, Loading action ; 36-39, Cartridge receiver; 40, Cover; 41-44, Parts of hand-lever ; 45-49, Traversing action ; 5<>-S5t Elevating and trailing action; S^, 57, Hopper and slide.
the Catling, the most important of the hand-operated machine guns was the Nordenfeldt, which was principally designed for naval use about the time when torpedo-boats were beginning to be regarded as dangerous antagonists.
1 The U.S. pattern Galling hardly differed except in details from the model, above described, of twenty years earlier. The drum had been set horizontally instead of vertically and improved in details, and a " gravity feed," a tall vertical charger, was also used. The barrels were surrounded with a light casing. Tests made of the improved Catling showed that the use of only one barrel at a time prevented overheating. On one trial 63,000 rounds were fired without a jam, and without stopping to clean the barrels. Smokeless powder and the modern cartridge case were of course used.
'The following particulars may be given of the 2-barrelled Gardner and 3-barrelled Nordenfeldt (land service) converted to take the -303 cartridge: Weight, 92 and 110 ft respectively; parapet mounting in each case 168 lb; rate of fire of Gardner about 250 rounds per minute, of the Nordenfeldt about 350. A few of these guns are still used in fortresses and coast defences.
succession. In this piece, careful aim can be taken from a movine platform, and at the right moment the barrels can be fired at the object almost simultaneously.
PRESENT DAY MACHINE-GUNS Hitherto we have been dealing with weapons worked by handpower applied to a lever or winch-handle, the motion of this lever being translated by suitable mechanism into those by which the cartridges are loaded, fired, extracted and ejected the cycle continuing as long as the lever is worked and there are cartridges in the " hoppers " which feed the gun. In the modern " automatic " machine-gun, moreover, the loading, firing, extracting and ejecting are all performed automatically by the gun itself, either by the recoil of its barrel, or by a small portion of the gases of explosion being allowed to escape through a minute hole in the barrel near the muzzle. The following details of the British Maxim, Hotchkiss and Colt types are reproduced from the article " Machine-guns," Ency. Brit. loth ed.
The idea of using the recoil, or a portion of the gases of ex- I Attached to the rear of the barrel (6) on either side are two side plosion, for the working of the breech mechanism is by no means g uides O works the aggregation of parts new, the latter system having been proposed and ^tw^l 'j^h 11 ^ (certainly in a very crude and probably unworkable form) by FIG. 6. Maxim Gun on Wheeled Carriage (1900).
(Sir) Henry Bessemer in 1854; but whatever might be discovered by a search in old patent and other records or in museums, there can be no doubt that (Sir) Hiram S. Maxim was the first to produce a finished automatic gun of practical value. His patents in connexion with this particular class of weapon date back to 1884, and his gun on the recoil system was, after extensive trials, adopted into the British army in 1889 and into the navy in 1892. It is very possible that Bessemer's idea did not bear fruit earlier because the fouling left by the old forms of " black " or smoky powders was apt to clog the moving parts and to choke any small port. With modern smokeless powders this difficulty does not arise.
The Maxim gun, 1 as will be seen from figs. 7 and 8, consists of two parts, the barrel casing (a) and breech casing (d), secured firmly together. The former (a), which is cylindrical in form, contains the barrel (6), and the water surrounding it to keep down the very high temperature attained by rapid fire, and the steam tube (c), which by the action of a sliding valve allows of the escape of steam but not of water. The barrel has asbestos packings at its front and rear bearings in the casing, which Maxim Qua.
the crank axle E, crank E', and connecting rod I (see figs. 7 to 1 1^7 The connecting rod I joins the lock and crank, being attached to the side levers J of the former by means of the interrupted screw U ; the latter enables the lock to be detached and removed.
The crank axle E extends through both sides of the breech casing (d), slots (k, fig. 7), allowing ~*it a longitudinal movement of about an inch. To its left-hand end, outside the breech casing, is attached the fusee chain Y of the recoil spring X (see dotted lines in fig. 7), and to its righthand end a bell trunk lever, B B'; the arm B, ""which terminates in a knob, being turned by the crank handle, the arm B' working against the buffer stop C.
In figs. 8, 9 and n the breech is shown closed, and it will be noticed that the crank pin I' is above the straight line joining the axis of the barrel, the striker T, and the crank axle E. As the crank is prevented from further movement upwards by the crank handle B taking against the check-lever G (fig. 7), it is clear that the pressure on discharge of the cartridge cannot cause the crank axle to rotate, and so open the breech as shown in figs. 10 and 12.
The withdrawal of the lock and opening of the breech are effected as follows: The total travel in recoil of the barrel is about one inch, but on discharge the barrel, the side plates and lock all recoil together for about a quarter of an inch without any disturbance of the locking as explained above, and by the time this short travel is completed the bullet has left the muzzle. The arm B' of the crank handle then engages the buffer stop C and causes the crank axle E to rotate and the crank E' to fall and so draw back the lock from, and open, the breech. At the same time the fusee chain Y is wound up round the left-hand end of the crank axle E and the spring X extended. In the meantime the knob of the buffer handle B swings over, and just as the lock reaches its rearmost position (as in figs. 10 and 12) strikes the flat. buffer spring H, and, rebounding, assists the crank in revolving in the reverse direction; the spring X also contracts, and, unwinding the fusee chain, draws back the lock again and closes the breech, a fresh cartridge having been placed in the barrel as explained below.
The gun is fired by means of the trigger F, which is actuated by the projection (I) on the trigger bar (S), the latter being drawn back when the button (m) on the push lever (n) is pressed forwards. If, therefore, the button he kept permanently pressed, the projection (/) will always lie in the path of the trigger F just as the lock reaches its forward position and the breech is closed, and the gun will fire FIGS. 7 and 8. Mechanism of Maxim Gun.
allow of its sliding in recoil without the escape of water. The breech casing (d) is a rectangular oblong box, and contains the lock and firing mechanism. At its rear end it has handles (e) by which the gun is directed, and the thumb-piece (m) by which the trigger is actuated. Its top is closed by a lid, hinged at (i). At its front is a recess holding the feed-block (/) through which the belt of cartridges (g) is fed to the gun.
1 Modern improvements in mechanical details are only slight, as may be found by reference to the official handbooks of the gun, editions of 1903 and 1907.
automatically, and continue to do so as long as there are cartridges in the belt.
The loading, extraction and ejection of the cartridges are effected as follows: The left-hand side-plate is extended forwards a little beyond the breech, and communicates the reciprocating motion of the barrel to a lever on the feed-block, which causes the cartridges in the belt to be fed forward one by one by a " step-by-step " pawl action, the cartridge which is next to be taken from the belt being arrested exactly above the breech, the ejector-tube Q being below in the same vertical plane.
The extractor D (see figs. 9 to 12) which performs the operations MACHINE-GUN of inserting, extracting and ejecting the cartridges, travels vertically in guides on the face of the lock. Projecting outwards from each side of its top are horns N (figs. 9 and 10). These travel round the edges of the cams M (fig. 8) situated on each side of the breech casing, and in conjunction with the spring W (fig. 8), compel the top of the extractor to take the path shown by the dotted lines and arrows in figs. 9 to 12.
FIG. 9. Maxim Gun Mechanism.
The extractor (figs. 11 and 12) is recessed to take a movable plate (M) termed a " gib," behind which is a spring (v). In the face of the gib is a recess (w) into which the base of a cartridge can just enter. On either side of the gib the face of the extractor has undercut flanges, open at the top and bottom, between which the base of a cartridge can fit the rim, being held in the undercuts (figs. 9 and 10).
It is clear from this arrangement that the base of the cartridge having been introduced between the flanges at the top of the extractor, can be pushed down, the spring (v) yielding, till arrested at the recess (w) ; and, as the lower edges of this recess are slightly sloped, further pressure will make it leave the recess (w) and slide over the face of the gib, leave it, and take up a position in front of the hole for the point of the striker (x), being now only prevented from slipping out of the extractor by the extractor spring (y). If this last be clear of the extractor stop (z) it will yield to pressure and the cartridge will be free. This "is the action in the gun except that the cartridge is held firm and the extractor pushed against it.
In fig. 10 the extractor holds a cartridge (r) and a fired case (g) ready to be pushed into the empty breech and ejector-tube Q respectively. In the latter there is already a fired case (p), which will be driven by the fired case (g) beyond the ejectoi spring R. As soon as the lock reaches the face of the breech, the cartridge (r) and case (g) are deposited in the breech and ejector-tube respectively, and the extractor D rises under the action of the levers L and J, slides, as already explained, by the bases of the cartriSges (r) and case (g), and then over the base of the cartridge (s) in the belt (g). Assuming the push-lever (n) to be pressed, the gun fires immediately this has occurred, and the bullet of the cartridge (r) is expelled. The position is now that shown in fig. o. The barrel now recoils and the lock is withdrawn, taking with it the fresh cartridge (s) from the belt and the now fired case (r). The extractor travels horizontally for a time and then drops (as shown by the dotted line and arrows), assuming the position shown in fig. 12, which is exactly similar to that in fig. 10 but with different cartridges; continuing the action, mechanism and the safety arrangement. The lock is cocked, after firing, by the arm of the " tumbler " K, being pressed down by the side lever J as it swings down when following the crank E'. Safety against firing before the breech is closed is provided by the projection on the safety lever V, which does not clear the striker T until lifted by the side lever J at the top of its travel, that is, when the crank E' has passed the axial line as already explained.
The lock in its rearmost position is kept in place by the block Z on the under side of the coyer of the breech casing. When in this position it is clear of the guides O on the side-plates, and if the cover be opened it can be turned up, unscrewed by a turn through an eighth of a circle (the screw-thread U being interrupted in four places) and removed. To prepare the gun for firing, the crank handle is pushed over by hand to the buffer-spring, thus withdrawing the extractor, and held in this position ; the tongue on the end of a filled belt is then pushed through the feed-block from the left and pulled as far as it will go from the opposite side. This places a cartridge above the breech ready to be seized by the extractor. The crank handle is now released and the lock flies forwards. The crank handle is now again pushed over and let go, and the first cartridge thus taken from the belt and placed in the breech. The gun is ready to fire.
To remove a partially filled belt, the crank handle must be pushed over, thus freeing the extractor from the belt, and the latter withdrawn after pressing a spring catch under the feed block which releases the pawls. The gun now has two live cartridges in it both in the extractor. Letting go the crank handle, one of them is deposited in the ejector-tube, and again pushing over and letting go the crank handle does the same with the second.
It will thus be seen that each cartridge makes two complete journeys with the extractor; the first as a live cartridge from the belt to the breech, the second from the breech to the ejector-tube, the forward journey being always on a lower level than that of the backward one. The sections in figs, n and 12 clearly show the cocking and firing FIG. ii. Maxim Gun Mechanism.
The gun is sighted to 2,500 yds. and has a folding tangent sight as shown. Its weight varies from 50 to 60 Ib, and it can fire about 450 rounds per minute.
[The diagrams have been made from drawings, by permission of Messrs Vickers, Sons & Maxim.] The Hotchkiss gun, figs. 14 to 16, wWh has been adopted by the French army and navy and elsewhere, depends for its action on the use of a small portion of the gases of the cartridge itself. The barrel A is firmly attached to the receiver or frame B, the latter containing the breech and firing mechanism. Under f htl the barrel A, and communicating with it by a port (c) . near the muzzle is a cylinder or tube C. When the gun is fired, and the bullet has passed the port (c), a portion of the gases of explosion passes into the cylinder C and drives back the piston F contained in it, a lug on the under part of the piston compressing the spring M, the latter, when the trigger N is pulled, driving back the piston again. The reciprocating motion of the piston performs all the processes of loading and firing the gun, and the action is continuous as long as the trigger is kept pressed back. The piston F, enlarged and suitably shaped at the rear, actuates the breech-block H and firing pin or striker J ; and, by suitable cam grooves (/) at about the centre of its length, works the larger feed-wheel U of the feed-box S ; the smaller wheel U on the same axis in turn imparting a step-by-step motion to the metal feed-strips, each containing 30 cartridges, so that fresh cartridges are placed one by bne before the face of the breech block ready to be pushed into the breech when the fired cartridge has been extracted and ejected.
On the under surface of the piston F, in rear, is a recess or sear (/) in which the nose of the trigger N engages, holding back the MACHINE-GUN piston when it has been driven back by the gases. As already stated, a lug on the under surface just in rear of the cam (/) engages with the front of the mainspring.
FIG. 12. Maxim Gun Mechanism.
Taking first the position shown in fig. 15 with the breech closed and locked and the cartridge fired, it will be seen that the breech is locked by the upper cam (/'), on the end of the piston, F, having caused the movable locking-dog (h) to fall and bear against the recoil blocks Z (see fig. 14 also) on the walls of the receiver or frame B. Consequently the breech is not unlocked until the piston has moved sufficiently to the rear for the lower cam (/') to lift the locking-dog (h) clear of the recoil blocks Z. As the piston F is not actuated by the gases until the bullet has passed the port (c), and then has to move a short distance before the locking-dog is raised, the bullet is clear of the muzzle before the breech is unlocked. As the piston continues to recoil it draws back the striker J and then FIG. 13. Maxim Feed-block, the breech-block H, and is then caught and retained by the engagement of the sear (/) with the trigger N, and the position assumed is that shown in fig. 14.
I the object of the arrangement being to enable the under surface of ' the breech-block to clear the clips which hold the cartridges in the I feed-strips. The cartridge therefore, being extracted in the line of the axis of the block, is ejected through an opening above its plane of entry in the feed-strip.
Returning to the position shown in fig. 16, if the trigger be pulled, the compressed spring M reacts and drives the piston forwards, carrying the breechblock with it, the latter in turn driving a cartridge in front of it out of the feed-strip. When the block and cartridge are home, and not till then, the piston completes its travel, the upper cam (/') locking the dog (h), and the firing-pin protrudes and fires the cartridge. Anything, therefore, which prevents the breech-block from being home against the breech, or the locking-dog from falling in front of the recoil blocks Z, renders firing of the cartridge impossible. Clearly if the trigger be kept depressed the action becomes automatic.
A special feature of this gun is the absence of a separate spring to actuate the firing-pin ; the recoil spring M performing this function, in addition to that of driving the piston forwards.
The feed-strips have holes in them in which the teeth of the smaller feed-wheel U engage. The engagement of this feed with the piston F can be released by pulling out the feed arbor W, so that the strips can be removed at any time.
When the last shot in a feed-strip has been fired a stop (V) holds the piston and block ready for a fresh feed-strip to be inserted. As the stop V acts quite independently of the trigger, this action takes place even if the trigger be still depressed after the last cartridge in a strip has been fired.
To cock the gun, when in the locked position, a cocking handle G is provided. This has a long arm projecting to the front with a catch which takes against the front of the lug on the under side of the piston. To prepare the gun for action the gun is cocked, and a feed-strip is pushed into the feed-block.
The pressure of the gas on the piston is regulated by the regulator screw D, by means of which the space in the cylinder C in front of the piston F can be reduced or increased.
A safety lock R is furnished, which is a " half round " pin which can be turned so as to enter the semicircular slot just in front of the sear (/), and so hold back the piston when in the cocked position.
Radiation of the heat, generated in the barrel by rapid fire, is facilitated by the radiator (a), which consists of rings on the barrel close to the breech, which offer an increased surface to the air.
HOTCHKISS AUTOMATIC MACHINE GUN Longitudinal Section Breech open Longitudinal Section Breech closed.
FIGS. 14, 15, 16. Hotchkiss Gun Mechanism.
From the head or nose-piece I of the breech-block projects the claw K of a spring extractor which, as the cartridge is pushed home by the breech-block, seizes it, extracting the fired case when the breech-block is withdrawn. Ejection of the fired case is effected by means of the ejector L (fig. 16) which catches against the base of the case, on the opposite side to the extractor claw, and so throws it sideways through the oblong-pointed opening in the receiver just in rear of the breech (see fig. 14).
The platform on the top of the feed-box through which the teeth of the smaller feed-wheel U project, and on which the feed-strips rest, lies below the axial line of the breech-block H, so that the face or nose-piece I of the latter only engages a portion of the base of the cartridge in the feed-strip as it pushes the cartridge into the breech, the bullet of the cartridge being guided into the breech by the incline at the opening of the latter. This point should be specially noted, The gun is sighted to 2000 yds., with the ordinary flap backsight, weighs about 53 ft, and can fire from 500 to 600 rounds per minute.
[The diagrams have been made from drawings, by permission of the Hotchkiss Ordnance Company.] The Colt automatic gun, which has been adopted by the American army and navy, and was used by the British in S. Africa, depends for its action, similarly to the Hotchkiss, on the escape coltOu of a small portion of the gases of explosion through a port in the barrel a short distance from the muzzle. Figs. 17 and 18 give a plan, and side elevation with the left side plate removed, respectively. Into the recess in the barrel (92) just below the port fits the piston (35), capable of slight motion round the pivot (36), by which it is attached to the gas lever (29). The latter is a bell-crank lever pivoted at (34), its short arm being attached MACHINE-GUN at (46) by a pivot to a long link with a cross head, termed the retracting connexion (45). This link extends from a point close to the figures (44), where the arms of the cross head bear against the ends of two long spiral retracting springs, (37) and (38), contained in two tubes, (39) and (40), which are slotted for a few inches of their length to allow the cross head to follow up and compress the springs. (Only (38) and (40) are shown, (37) and (39) lying in the same plane of projection.)
When the gun fires, and the bullet has passed the port, the gases drive the piston (35) and gas lever (29) downwards, and the momentum imparted causes them to swing back round the pivot (36), as shown by the dotted circle. The gas lever is brought up now by the bottom plate (91); and the retracting springs, compressed by the cross head of the long link (45) owing to the forward motion of the short arm of the gas lever, react and drive the gas lever into its forward position again.
The rotary movement of the gas lever is converted into a reciprocating movement of the slide (86) by means of the gas lever connexion rod (31) pivoted at (32) to the gas lever, and at (87) to the slide.
The slide (86) is a nearly flat bar, travelling in guides in the receiver, extending from (14) to (87). It is slotted completely through longitudinally for nearly the whole of its length, this slot affording an opening through which work the cartridge extractor (82) and carrier (21). At its rear end it engages by means of a pin (14) in a cam slot (97) in the bottom rib of the bolt (13), and at (83) it bears the pivot of the cartridge extractor (82). Its rear end is enlarged below to form a cam lug (98), and on its right side are two projections (95) and (96), which work the feed lever (66).
FIG. 19. Colt Gun mounted.
The feed wheel (61), over which passes the belt containing the cartridges, is actuated by a pawl " step-by-step " gear by means of the feed lever (66).
The carrier (21) is a long trip lever pivoted at (22), and provided with a spring dog (23) pivoted at (24).
The bolt (13) is a cylinder with a guide rib extending from its under surface. It is actuated by the slide by means of the pin (14) and cam slot (07) as already stated, and is bored through to take the striker or firing pin (18). The rear end of the latter projects slightly beyond the rear face of the bolt, being retained in this position by the spring (19). When this projecting end is pushed into the bolt, the point protrudes from the front of the bolt and fires the cartridge. The bolt, when the breech is locked, is held firm by two recoil blocks on the receiver (not shown), as is explained later. At the front of the bolt is an extractor (15) with a spring claw for extracting the fired case. (This is of course quite distinct from the cartridge extractor (82).) Ejection is effected by means of an ejector projecting into the path of the fired case.
The firing of the gun is performed by the cylindrical hammer (6) hollowed out in rear to contain the mainspring (7). When pushed back and cocked as shown in fig. 18, it is held during a portion of the operations of the mechanism by two detents working independently of each other the sear (10) and the nose of the trigger (8). The former is automatically released by a trip lever (not shown) as soon as the breech is locked, leaving the hammer held by the trigger only. This is the position shown in fig. 1 8. The necessity for the two detents is explained later.
The hammer, when cocked, can also be permanently locked by the handle lock (2) actuated by a thumb-piece on the outside of the receiver. The air compressed in rear of the hammer, as the latter is driven back, passes through the tube (99) to the breech ; and a puff of air is therefore blown through the barrel after every shot, clearing out fouling and unconsumed powder, and assisting to an appreciable extent to keep down the temperature of the barrel.
Taking the position shown in fig. 18, the hammer is only held back by the trigger nose, the sear (10) having been released as stated above. A belt of cartridges (not shown) has been placed on the feedwheel, and the cartridge next to be used after the one (not shown) now in the breech has its rim (or base with rimless cartridges) just above the hook on the extractor (82). If now the trigger be pulled, the hammer flies forwards, strikes the protruding end of the firing pin, and the cartridge fires; the gases cause the gas lever to swing round and drive back the slide. The pin (14) working in the cam groove (97) causes the rear of the bolt to rise and clear itself from the recoil blocks (not shown) on the receiver, and then to move rearwards horizontally, driving the hammer back until the latter is caught and held by the sear and trigger. In the meantime the extractor (82) has pulled a cartridge from the belt, and, assisted by two spring cartridge guides (80 and 81), of which only (80) is shown, deposits it on the carrier (21) ; the projection (95) strikes the feed-lever (66), and moves the feed mechanism so as to prepare to revolve the feedwheel and place a fresh cartridge ready for the next round ; and as the slide completes its travel backwards, the cam (98) strikes the dog (23) and slightly depresses it (the spring (25) yielding), the MACHINE-GUN carrier and cartridge on it consequently rising a little and falling again (this latter action is incidental only to the form of the parts, and is not a necessity).
The retracting springs now react and pull the slide forwards; the cam (98) strikes the dog (23), which, as the spring arrangement is of the " non-return " class, does not yield but is depressed, and the FIG. 20. Hotchkiss Gun mounted.
front of the carrier and the cartridge on it are therefore raised sharply, and the latter placed in the path of the bolt. The bolt being now pulled forwards, the cartridge is driven off the carrier into the breech, and the bolt locked by the pin (14), causing the bolt to drop in front of the recoil blocks; the carrier is pushed down flat by the advance of the cam lug (98), the trip releases the sear (10), and the projection (96) pushes back the feed lever, completing the action of feeding a fresh cartridge forward. The position shown in fig. 17 is now resumed.
It is clear that were the trigger kept permanently pulled the gun would fire immediately the bolt was locked and the sear (10) depressed, and the action would become automatic.
The object of two detents, though now probably obvious, may here be explained. The whole action of the gun depends upon the hammer after it is pushed back by the bolt being held back until the bolt has gone completely forwards and locked the breech. If only the trigger detent existed, and that were kept pressed down, the hammer, after being pushed back by the bolt, would immediately follow up the latter, and might fire the cartridge prematurely, or fail to fire it at all; hence the use of the sear in addition to the trigger.
To cock the lock, or work the mechanism by hand, the gas lever is pulled round by the pin (30) provided for the purpose, and by this means the gun is prepared for firing. A brass tongue on the end of the belt is pushed through the opening above the feed-wheel and then pulled from the other side of the gun as far as it will go. This places a cartridge in front of the extractor, and if the gas lever be now pulled right back and let go, this cartridge is placed in the breech as already described, and the gun is ready for firing. If it be desired to remove a belt from the feed, a button (68) is pressed and the feed-wheel is then free to revolve backwards.
The gun is sighted with the ordinary rifle-pattern sights, up to 2000 yds. or more if required. It weighs about 40 ft, and can fire about 400 rounds per minute as usually adjusted, though this rate can be increased. There is no means of altering the gas pressure in the field as with the Hotchkiss.
[The diagrams have been made from drawings, by permission of the Colt Arms Company.] Comparing the principle of employing a recoiling barrel with that of using a portion of the gas, the advantages of the former are that the recoil is made to do useful work instead of straining the gun and mounting in its absorption; the latter system, however, has undoubtedly the advantage in simplicity of mechanism (the Hotchkiss is extraordinarily simple in construction for an automatic gun), and in the large margin of power for working the mechanism with certainty in all conditions of exposure to climate, dust, and dirt. While inferior in this respect, it is nevertheless the fact that the Maxim has proved itself in the field even in savage warfare in the roughest country to be a very efficient and powerful weapon.
The great difficulty which has to be met in all single-barrel machine guns is the heating of the barrel. The 75 pints of water in the water-jacket of the Maxim gun are raised to boiling point by 600 rounds of rapid fire i.e. in about 15 minutes and if firing be continued, about i j pints of water are evaporated for every 1000 rounds. Assuming that the operation is continuous, the rate of waste of energy due to heat expended on the water alone is equivalent to about 20 horse-power (294 foot tons per minute). The water-jacket acts well in keeping down the temperature of the barrel; but apart from the complications FIG. 21. Tripod mounting (Mark IV.), for British Maxim.
entailed by its use, the provision of water for this purpose is at times exceedingly troublesome on service. In the Hotchkiss and Colt guns, which have no water-jacket, an attempt is made to meet the heating, in the one by the radiator, and in the other by a very heavy barrel.
One of the most modern types of gun is the Schwarzlose, which is manufactured at Steyr in Austria, and was adopted by the Austrian army in 1907. This weapon is remarkable for its simplicity. There are only 10 main working parts, and any of these can be replaced in a few seconds. It is operated by the gases of the explosion, has a water-jacket that allows 3000 rounds to be fired without refilling. The " life " of the gunbarrel is stated to be 35,000 rounds without serious loss of accuracy. The weight of the gun is 37-9 Ib. It is a belt loader.
The Italian Perino gun, adopted in 1907, is a recoil-operated weapon, and is loaded by a metal clip. The Skoda gun, some of which type are used in Japan and China, is loaded by a hopper feed, and is gas-operated. The Bergmann gun is a belt loader, but the belt passes down a " gravity feed " an arrangement which saves a number of working parts.
One defect common to all is that it is by no means easy to proportion the fire to the target, as there are only two rates of fire, viz. rapid automatic and slow single shots. To fire a single shot requires practice, since the gun will fire some 7 shots MACHINE-GUN in one second, and to press the trigger and remove the finger or thumb instantly, and at the same time be ready to traverse to a fresh target, requires considerable skill.- The result of these difficulties is that the target when struck is often riddled with bullets when one would have sufficed. The aiming of the gun, when rapid fire is taking place, may also be difficult even on firmly fixed mountings, owing to vibration. The greater delicacy of the modern machine gun has been alluded to above. 1 Nevertheless the advantages of safety, steadiness and lightness which the automatic weapon possesses, have ensured its victory over the older type of weapon, and although the simple strong and well-tried Galling still has its advocates, every civilized army has adopted one or more of the automatic types.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)