The very finest powder, it will be perceived, is fitted—perfectly fitted, preferable, indeed—to coarser grain for guns of a short length of tube, where a perfect combustion of the whole charge can be obtained without any waste or want; but as such is quite unsuited for longer barrels: I cannot too often repeat it. The column of air is the ruling power. Look what its effects are by Hutton’s calculations, with the very low velocities he obtained! So great as to bring all projectiles he used to a medium velocity, before they were projected beyond a certain distance. Then what must its resistance be where the velocities are trebled? I say trebled, for my powder and the percussion combined have more than trebled the velocities. You must then clearly have a powder of such grain as suits the capacity of your gun. All barrels have a size of grain that will suit them best, and manufacturers of gunpowder will consult their own profit and the convenience of sportsmen, if they assimilate the grain of powder to various sizes; as in shot, to No. 1, No. 2, 3, 4, 5, and so on: eventually this system must be adopted.
This will explain quite clearly how the fact (singular to many) occurs, of short guns excelling their longer competitors, and how frequently a particular maker obtains an immensity of credit for an excellent gun only twenty-two inches: “Beat my Lord So-and-so’s of thirty inches!” and how, “When I cut four inches off my double, she shot better than ever she did.” All these occurrences are perfectly dependent on a knowledge of the generating of the explosive force, and may be reversed at any time by a person possessed of sufficient knowledge of these facts: put in coarse grain into the short gun, and fine into the long, and the facts will be changed considerably, as will be easily seen. A degree of mystery has hitherto existed as to the cause of this discrepancy; but I trust this explanation will clear it up.
Experiment has shown the error of stating that only a certain quantity of powder could be consumed: the proportion stated was considerably below the actual quantity, as the experiments of punching the plates show; for since twelve drachms can be burnt in a three-feet barrel, therefore ten drachms may be consumed in one two feet eight inches, with a given weight to lift. In addition to this, must be placed the fact of improvement, both in the composition and granulation of the powder; which we have no hesitation in stating has been considerable, within only a very few years, all tending to the quickness of generating force. The granulatory system, if acted upon, will give the sportsman or soldier a completely new power in gunnery; for it must be evident, if we have the means of projecting certain bodies with an extreme velocity, say 5,000 feet per second, it becomes a simple calculation to ascertain the quantity of force and length of tube to give to a certain weight. Take, for instance, an ounce ball in a barrel two feet six inches long. Extremely fine grain powder, from its rapidity of expansion, gives to the ball this velocity at fifteen inches from the breech; the remaining fifteen inches contain a column of air highly condensed, which will inevitably reduce this velocity back nearly fifty per cent., or 2,500, and with that velocity the ball leaves the muzzle. Therefore, as we have already said, it must be evident you have here generated a high speed to be as quickly reduced; and it shows clearly that if a different grain of powder would expand from breech to muzzle, increasing the velocity on a granulated scale until it obtained the highest, or 5,000 feet per second, as the ball left the muzzle, you would save here clear 50 per cent. in force, with less recoil, less internal strain on the barrel, and with exactly the same weight of powder; thus showing that you have just a definite quantity of force in a definite quantity of powder.
The true science of gunnery is the knowledge how to best arrange the collateral parts, so that you may obtain the greatest result with the least means. I have also clearly shown that the resistance of the atmosphere is one, and the principal obstruction in the attainment of high velocities; its resistance being regulated entirely by the degree of speed with which it is wanted to be displaced. Thus it is true, as both Robins and Hutton have shown, that only a certain velocity can be obtained beneficially; though the degree is considerably greater then either conceived, as far greater impetus has been obtained, and projected bodies have ranged much beyond their calculations, and that beneficially too. One drawback on the theory of these gentlemen is their calculating the velocities with iron projectiles; for the heavier the material the more powerful the momentum, and consequently the longer retention of their velocity, from not presenting the same space to the resisting medium, the air.
The development of the system of granulation must and does exercise considerable control over the shooting of barrels of every description. I have already explained what has been hitherto considered the curious phenomena of short and long barrels shooting so dissimilarly, and this illustration completely establishes the fact of the expulsive and repulsive forces being controlled by each other: as either preponderates, so is the result. The open-ended barrel projecting balls, and eventually bursting, is a beautiful and interesting elucidation, both of the force of gunpowder and the stubborn nature of the atmospheric fluid. All these facts are valuable, inasmuch as they lay bare circumstances which have never been satisfactorily accounted for, and enable the mind of lowest capacity to understand the cause and effect.
The superiority of one barrel in throwing shot stronger and more evenly distributed, arises, it will be easily seen, from the absence, or existence of, internal friction, when contrasted with the different degrees of expelling force, and the degree of resistance from the atmosphere; it also accounts clearly for the fact of guns shooting stronger on one day than on another, in fine and in rough weather: the weight, the resistance of the air, is the only cause of the variation; for gunpowder cannot drive back a dense atmosphere as quickly as a lighter one. The cause of guns bursting is to be placed to the account of both air and the generation of the explosive fluid so instantaneously; the solid front which air offers to quick compression, throws the force on the barrel, and the sides of the tube give way because they are weaker: this cannot occur so easily with powder of a more gradually expansive force, therefore safety is consulted in its use, in addition to the numerous advantages it otherwise possesses.
Mr. Blaine, in his Encyclopædia of Rural Sports, has the following: “The increase of metal in the detonator, we think, with Colonel Hawker, to be an essential requisite, first, to resist the quicker, and, consequently, more forcible, expansive force applied by the ignition of the powder through the agency of detonation, and tend to lessen the recoil so much more forcibly felt in most detonators. This increased weight of percussion Mr. Greener, however, objects to, and inquires, ‘Whether some of the best flint guns met with, have not been very light?’ To this we answer, that it was the principle on which the explosion of the flint gun was effected that enabled it to be made lighter, and yet to remain equally safe in using; but we also know, that where it was required to add to the rapidity and force of the ignition, it then became necessary to increase the substance of the barrel.”
Experience teaches the writer, and I dare say it would Mr. Blaine, if he were to experiment to the extent I have done, that there is no rapidity in the ignition further than the closing of that point of ignition by the cock, and no “force” beyond what the comparative instantaneous ignition of the gunpowder in the nipple creates. This is quite sufficient to prevent the further penetration of the percussion flame; and the only increase, to quote his own words, “to resist the quicker, and, consequently, more expansive, force applied by the ignition of the powder through the agency of detonation,” arises from an improvement (as it is termed) in the granulation of the powder, which alone creates the increased expansive force. This will be clearly understood by any one reading this work from the beginning; the only difference between the flint and percussion systems is the stopping of the orifice of ignition in one, and allowing it to escape in the other; for the flame has to travel to windward (to use a nautical expression) in the flint; the other has its own accumulating power to force ignition through the body of the powder. This alone constitutes the difference. The necessity for an increase of metal at the breech of a barrel does not arise from any peculiarity in the mode of communicating the fire, but in the increased inflammability of the powder alone. The extreme smallness of grain has effected this more than the use of fulminating flame; and the continuous cry for fine powder, to get better up the nipples, has produced an alteration which is placed wrongfully to the credit of the percussion.
Again, he says, “Mr. Greener, however, would have us acquire this increase of power of resistance, not by quantity of material, but by increased tenacity and elasticity in the metal the gun is formed of, and we agree that it would be a great improvement if it could be brought about. But what is our prospect of it? Is it not the general complaint that gun metal is not by any means what it was? We have shown that it is not; and, therefore, we do not think, as Mr. Greener asserts, that any recommendation of increased weight of metal to the percussion barrel beyond that of the flint gun “is founded on ignorance;” but, on the contrary, that the very reason Mr. Greener gives to prove it, is that which we think affords evidence of its perfect rationality, the explosive force created.” The answer given above applies to this also: save on the score of lessening recoil, superior quality is preferable, to quantity.