Muzzle velocity

“ If the muzzle velocity is normal, no correction is made for velocity. If, however, the muzzle velocity is not normal, he makes a correction for muzzle velocity in a similar manner as for other data.
The above corrections are made before the travel is received. The computer clamps the bar and then waits until he receives the travel.
As soon as the travel is received, he sets the string, slides trammel until the pointer is opposite the string, unclamps the bar and moves it until the pointer is opposite the normal; this adds the correction for travel during the time of flight. ”

“ In England the term muzzle velocity is frequently used. In gunnery, the initial velocity of a projectile is the velocity at the muzzle of the piece, and is determined by the use of the ballistic pendulum, the gun pendulum, the electro-ballistic machines, the Schultz chronoscope, or the Le Boulengé chronograph ”

“ Hence the shell must have 156,800 units of momentum, which may be composed of high velocity and light weight, or low velocity and heavy weight. For breaching purposes, accuracy and penetration are essential qualities ; a shell varying in length from two and a half to three times its diameter will be suitable for the purpose. We have now a neat problem in ballistics, viz., To find the calibre of a shell of the proper length, of such a weight that, with the muzzle velocity required to give a range of 1500 yards at 5 elevation, the muzzle momentum shall be 156,800 units. ”

“ The energy imparted to it at the muzzle amounts to 6,408-foot tons assuring a penetration at the muzzle of 33.8 inches of steel, or at 3,500 yards of 27.5 inches, the muzzle velocity being 1,975-foot-seconds and powder charge 640 pounds of smokeless. The maximum pressure in the powder chamber allowed is 37,000 pounds per square inch.
Briefly the modern gun is a built-up piece, constructed by fitting or shrinking super-imposed hoops or cylinders one over the other in size and number as diagramatically explained in Fig. 25, sufficient to re-inforce the bore to withstand the varied pressures. ”

“ Assuming the average height of a man to be six feet, all the distance intervening between the point where a bullet has dropped to within six feet of the earth, and the point where it actually strikes is dangerous to any one in that interval, which is called the “danger zone.” A higher initial velocity is gained by using stronger firing charges, and a more extended flight by making the projectile longer in proportion to its diameter. The reason why a shell from a cannon travels further than a rifle bullet, both having the same muzzle velocity, is easily explained. ”

“ The height to which aircraft artillery will carry is by no means subject to the same limitation as that of the small-bore machine-gun or rifle, the resistance of the air being many times greater than that due to gravity. Thus the ordinary rifle bullet, at 2,000 foot-seconds muzzle velocity, would carry to a height of over 60,000 ft. ”

“ ORDNANCE. riflia; the bore the less is the breech pressure required to produce a given muzzle velocity, and the less is the maximum strain thrown upon the studs, gas check, or other rotating agent ; next, the more forward the general disposition of the metal, the farther from the breech end will be the centre of gravity, j and consequently the trunnions, a position which favours steady shooting and absence of jump ”

“ The muzzle-velocity of the projectile is 2100 feet per second, with the stated charge, and its energy is sufficient to send it through 26 inches of steel at a distance of 600 yards. At an elevation of 40 degrees the range of the gun will be not far from 15 miles. ”

“ With guns having a muzzle velocity of 2,500 feet per second, it is no longer necessary for sportsmen stealthily to stalk their game to come within easy range, and as for hounds, they have become a doubtful appendage to the chase. ”

“ A bullet is forced out of a gun by the sudden expansion of gases behind it, but after it leaves the muzzle and the influence of the gases, why does it keep on traveling? We may just as well reverse the question and ask why it should ever stop. Having once acquired a certain velocity it keeps that velocity because of its inertia or mechanical helplessness, and it would keep on going forever were it not for the resistance offered by the air and the pull of gravity, which gradually draws it down to earth. [337] It takes a deal of energy to divert the bullet from its course. ”

“ It is an undisputed law in motion that one body may convey to another, by contact, nearly its own velocity, but in so doing, is sure to come to rest immediately. Strike one billiard ball against another, if the blow is centrical, the ball struck receives the motion, the other comes to rest; and so is it with shot: it is only the layers next the muzzle which strikes the target, the remainder fall without travelling the same distance. I have fired three balls from a rifle, and having marked them I found the uppermost projected farthest, and the others in proportion. ”

“ A projectile is set in motion gradually, and is (or should be, if the quality and quantity of the powder, and the barrel, have a right proportion to each other) at its greatest velocity just before leaving the muzzle; consequently the tendency of a ball would be to yield to the increasing force of the powder and pass straight out of the barrel without following the grooves ”

“ Thus, while not exceeding the intended pressure at the breech, the pressure toward the muzzle is kept up, and the velocity very materially increased. Following this principle to this conclusion, it will be found that the perfect charge for a gun will be one which exactly fills the chamber, and which is composed of a powder rather too slow to give the pressure for which the gun is designed, supposing the shot to move off freely. The powder should be so much too slow as to require for its full development the holding power of a band which is just strong enough to give rotation to the shot. ”

“ It is certain, then, that the shot must travel the latter half of the barrel at a diminished velocity, and its velocity must continue to diminish as it passes up the barrel; for two obvious reasons—1st, The column of air in front of the charge is more condensed, and thus offers a greater resistance to the exit of the charge; 2nd, The velocity is continually diminished by the increased friction of the charge against the barrel.
The perfection of projectile science is to make the projectile acquire its greatest velocity at the instant of leaving the muzzle ”

“ A 35-pound howitzer shell and an 18-pounder shrapnel, such as that fired by the British field artillery, were sent on their mission of death from guns of practically the same weight. Thus greatly did an increase in muzzle velocity mean a corresponding increase in avoirdupois.
Thirty-eight hundredweight was generally agreed by gun-experts the world over to be the weight permissible for field pieces; this limit being imposed by questions of mobility and transport. ”

“ The rapid exit of the bullet from the barrel, with a resisting influence of this weight into the comparatively insignificant one of 15 lbs. to the square inch, will fully explain how it is that a bullet increases in velocity even up to a considerable distance after leaving the muzzle of the gun ”

“ The power of a modern rifle is limited only by the power of the shooter to withstand the effect of recoil and to use a heavy piece. The momentum of the ballet forwards up to the time of its leaving the muzzle is equal (neglecting the weight and motion of the gas generated by the powder charge) to that of the gun backwards at any instant. Supposing the gun to weigh 150 times as much as the bullet, it will acquire a velocity against the shoulder equal to the 150th part of that acquired by the bullet. ”

“ If the velocity of gunpowder be as great as we suppose it to be, the displacement of a column of air must be effected by driving the whole column in a gun-barrel of many inches, into a column probably less than half an inch in height; or, if the length of the tube from the starting of the charge to the muzzle be 38 inches, then will the displacement require a force capable of condensing thirty-eight atmospheres into one, or something like 570 lbs. ”

“ But no sooner does the bullet quit the muzzle, than it immediately comes under the influence of another force, called the force of gravity, which differs from the force caused by the explosion of the powder, which ceases to influence the bullet, after it has once communicated to it its velocity. ”

“ Hence, as the shot travelled down the bore continual increments of gas were generated imparting an augmenting velocity to the projectile, which should reach the muzzle when this was at maximum. If the gun was too short, a large portion of the powder would be blown out unconsumed, and result in wasted energy. Even with considerable addition to the length this occurs in a minor degree, as can be seen by an instantaneous photograph of a gun at the moment of discharge. ”

“ Instead, therefore, of the pressure falling rapidly, as the shot approaches the muzzle, the increasing quantity of gas tends to make up for the increasing space holding it. You will at once perceive that the slower the combustion of the powder the less difference there will be in the pressure exerted by the gas at the breech and at the muzzle, and the greater will be the advantage, in point of velocity, of lengthening the bore, and so keeping the shot under the influence of the pressure. ”

“ Speeds vastly higher than those of ships are given to projectiles. A ball leaving a gun muzzle with a velocity of 3,410 feet a second, as at Sandy Hook in January, 1906, suffers great atmospheric resistance, overcome in part by the shot having a tapering or conoidal form. ”

“ The distance to the target divided by this time gives the initial velocity approximately. Practically, this method is only applicable to large breech-loading cannon, which have neither windage nor vibration in the barrel to affect the angle of departure of the projectile. Smooth-bores or muzzle-loading rifles are subject to the first cause of error; the first-named guns in a great degree, and small-arms to vibrations not yet fully investigated, which cause a sensible difference between the axis of the piece as pointed and the line of fire. ”

“ If the gun muzzle has to move 5 feet a second to get ahead of game crossing at 20 yards away, it need move but 21⁄2 feet per second to get ahead of game 40 yards away and moving at the same velocity. Consequently, when the whole allowance is given unconsciously by swing, and is just enough at 20 yards, it is clear that the same swing will only give the same unconscious allowance at 40 yards, and that this will not be half enough at that range, where the pellets are travelling slower and have double the distance to go. ”

“ Our fault was not in reverting to muzzle loading, but in retaining the system after the introduction of slower burning powder, which required a long gun to utilise all its energy. The new combination gave increased velocity, range, and penetration. As is well known, the path of a shot in the air is a curve, owing to the action of gravity. The quicker it is in travelling the less time there is for gravity to act, and consequently the more nearly does the projectile travel in a horizontal line. ”

“ Long barrels are useless, because all the velocity that can be given to the projectile has to be generated in the revolving chambers; all the superfluous force escaping at the joint of breeches and barrels. For any useful purpose, a nine-inch would be better than a longer barrel, allowing the bullet to leave the muzzle at a much higher velocity than it would do after passing through a barrel of thirty inches. It is evident, indeed, that [398] a revolving pistol and a revolving rifle are possessed of power in inverse ratio to their lengths. ”

“ The rate at which the work of giving rotation is done during the travel of the projectile from breech to muzzle is an entirely different question. If a shot be rotating, its tendency is, putting friction aside for the moment, to continue to rotate with the same velocity. No work is done in keeping up this rate of rotation, but work would be done in accelerating or retarding it. Thus in apportioning the work done on the shot in giving rotation Umf< at different parts of the bore, we have to consider, not the aiul i actual angular velocity, but the increments of angular "^ velocity. ”

“ It is generally considered that with studded muzzle-loading service projectiles, having a length equal to about 2 to 3 times their diameter, the velocity of rotation of a surface point of about 110 f. s. is sufficient to keep them steady, allowing for loss of spin by atmospheric friction up to any probable range. Supposing the interior of the gun to be opened out and laid flat, the groove (of a uniform twist) will be straight, and since the shot guided by it makes a complete revolution in n calibres, the angle made by the groove with a line parallel to the gun s axis may be expressed by tan -. ”

“ It must be borne in mind, also, that rapidity of revolution does not fall pari passu with that of velocity of flight, but that the former undergoes a comparatively slighter diminution until the bullet is actually spent. Hence, the influence of revolution is felt, however low the velocity may be, provided sufficient striking force is retained to enter the body. A word must be added here as to the surface of a discharged bullet; this, in taking the rifling of the barrel, becomes permanently grooved. The depth of the groove differs with the variety of rifle. ”