In order that “fire” may be “effective,” it is necessary to bring the enemy within the zone beaten by 75 per cent. of shots, and it has been found by experiment that 25 per cent. of shots fall immediately in front and behind the target, then 12½ per cent., 7½ per cent., and, finally, 5 per cent. scattered far in front and behind.

Diagram II
TO SHOW THE DISPERSION OF BULLETS

Infantry usually fire at the rate of three rounds a minute “slow,” and fifteen rounds a minute “rapid”; “slow” fire is the ordinary rate, and “rapid” fire can only be effectually maintained for about four minutes; but this is when the firer is fresh, and has not been subjected to several hours’ marching and fighting as would be the case in battle, and it is doubtful if “rapid” fire can be kept up on service for more than one-and-a-half to two minutes without becoming wild and consequently ineffective. On the other hand, “rapid” fire is less tiring to the machine gunner than “deliberate” fire; the gun is held for him by the mounting, it loads and fires itself, while elevation and direction are maintained without the least exertion on his part by the elevating and traversing gears.

In comparing the volume of fire of the machine gun with that of a body of infantry, it is obvious that “rapid” cannot be taken as the normal rate of infantry fire, as it can only be used for the shortest periods, and even then it reduces the users to a state of inefficiency as regards accuracy in two or three minutes. On the other hand, “rapid” fire can only be used by the machine gunner on special occasions, for tactical reasons which will be explained later, so that it will be necessary to compare “slow” infantry fire with “deliberate” fire from the machine gun, in order to arrive at the mean fire volume of each. Seventy shots a minute can easily be fired “deliberately” from a machine gun, and this could be increased to 120 by highly trained gunners, but, taking the lower figure, deliberate fire equals in volume the fire of twenty-four men using rifles. But it must be always remembered that the object of the fire fight is to bring a concentrated and overwhelming fire to bear at the right moment on certain positions of the enemy, and when the moment arrives machine guns can and will use the most rapid rate of fire possible, which will be from 250 to 300 rounds a minute or equal to that of 50 or 100 riflemen. Mere volume of fire, however, is useless without control, accuracy, and concentration, and it is here that the machine gun is so vastly superior to the rifle; for amongst 50 men using their rifles there can only be a small percentage of good shots, while even among the good shots unforeseen factors, such as fatigue, bad fire positions, excitement, wrong sighting, failure to see the target, etc., cause a large percentage of the shots to go astray, and make it very difficult to concentrate the fire on any particular position of the enemy.

An object-lesson to illustrate this superiority of the machine gun has been carried out during each course at the South African school of musketry under circumstances most favourable to the rifles. The record of one such test, carried out on September 21st, 1904, between a Maxim gun mounted on Mark III. tripod and 42 rifles (Lee Enfield), was published. The machine gun was worked by two sergeant-instructors, while the 42 rifles were fired by students who were all, at least, 1st Class shots before joining the school, and who for five weeks had been receiving daily instruction in musketry, and had just completed a course of firing both on the ranges (Table B) and in field-firing, and had gone through a course of judging distance. The range was unknown—the number of rounds unlimited, and the rate of fire “rapid.” The time was limited to one minute, and the firers were allowed to charge their magazines before starting. The targets were figures representing infantry in line extended to two paces. The following was the result:

Rounds
fired.		Hits.Percentage.Figures
hit.		Percentage
of loss.
Rifles4086215·12754
Maxim2286930·23264

The small number of rounds fired by the Maxim was due to the necessity of picking up the range by firing small groups of five or ten shots and observing the strike of the bullets. What is most interesting is that although the rifles fired nearly twice as many shots as the machine gun, the latter made actually more hits, while the percentage of loss inflicted was 10 per cent. greater. The actual range was 1,000 yards. A similar experiment was carried out during the annual training for 1908 in the U.S.A. between 42 “sharpshooters” and a Maxim at the regulation “L” target. The ranges were 600, 800, 1,000 yards; the sharpshooters fired an average of 750 rounds at the three distances and made an average of 429 hits, which gave a collective figure of merit of 59·09. The machine gun also fired 750 rounds, made 601 hits, giving a collective figure of merit of 79·54, being 22·45 in favour of the machine gun. The troops were armed with new rifles, and fired the new “S” bullet, while the machine gun used the old pattern ammunition and a barrel that had fired at least 7,000 shots. The gun squad had no previous practice at this target, and the gun was fired by different men at the several ranges. The collective fire of the troop was “slow aimed,” while the fire of the machine gun was “rapid continuous” for the number of rounds at each range. The machine gun took 30 seconds to fire 250 shots at each range, or a quarter that of the troop.[1]

The two experiments are particularly interesting, as showing how closely the results agree, although the conditions are dissimilar in one respect: viz. that in the first case the number of rounds was unlimited and the result had to be obtained within one minute; while in the second case time was unlimited, but the number of rounds fired by each was the same. The result of the two experiments show that both in accuracy and rapidity a machine gun is much superior to 42 picked shots, whether firing the same number of rounds at known ranges or firing an unlimited number of shots in a given time at an unknown range. We shall not be wrong, then, if we say that a machine gun is at least equal to 50 rifles in fire value,[2] but there are other factors to be considered as well as fire effect in determining its tactical value, and it is in these other factors that machine guns are so far superior to riflemen as to make a reliable estimate of their relative value almost impossible; these factors are: (1) Mobility; (2) Visibility; (3) Vulnerability.

Mobility.—The mobility of the infantry soldier is limited to the rate at which he can march, which on the battlefield is about 100 yards a minute or less than three-and-a-half miles an hour. Doubling may be left out of the question, as it quickly reduces fire efficiency to a minimum. An experiment made in the Austrian Army showed that the percentage of hits which was 76·5 per cent. after an advance in quick time, fell to 51 per cent. after doubling.[3] The mobility of the machine gun will depend almost entirely on the way it is carried, and must not be judged by any particular carriage which may happen to be in use for the time being in our own service. A short description of these mountings and their method of transport will be found in Chapter IX., but none of them are entirely satisfactory.