WHY GUNS ARE RIFLED.

Thames Star, Volume LVIII, Issue 18325, 26 April 1917, Page 7

WHY GUNS ARE RIFLED.

On looking througn tne bore of a rifle or a big gun a number of spiral grooves are to toe seen running he whole length of the bore from the breech to the muzzle. These grooves constitute the "rifling*' of the weaons. They serve to make the bullet and shell spin in tbeir flight through the air. Before the Introducion of rifling it was onV possible to use projectiles of spherical shape. Guns were "muzzle-loaders.'' The propelling charge of powder and the ball were rammed into the guns from, the muzzle end, and the weapons were discharged through the medium of a touch-hole. There are two great advantages of the rifled gun over the old smooth: bore. Rifling makes it (possible to us© a cylindrical projectile with a pointed head, and also gives the projectQe> that steadiness in flight which is soimportant for accurate marksmanship. Now, take the case of the modern breech-loading rifled gun. Io» stead of a round shell, which was used with the muzzle-loader, an eloneated cylinder, with pointed head, is employed. The diameter is the same in each case, but there is much greater weight of metal with the cylindrical shape. Near the base of the modern shell is to be noticed a smooth ring of copper, called the ""driving band." It is somewliat larger than the diameter of the shell itself, and it is firmly and immovably fixed to the steel shell by special methods. When the breech block of the gun is opened the shell is rammed home. The shell passes into the bore as far as the driving band, which prevents , its further ingress. The charge of cordite, enclosed in bags in the case of very big guns, is then placed in position behind the shell, and the breech block closed. When the gun is fired the cordite is quickly consumed, and an enormous amount of gas is rapidly produced. The shell is pushed forward, and the copper driving band being softer than the steel of the bore is forced to "take" the rifling. When the shell merges from the muzzle the hitherto smooth copper band has been out into by the rifling, giving it a corrugated appearance. The spiral rifling has cut grooves of slanting shape into the band, serving to rotate the projectile, which leaVes the gun spinning with considerable velocity. This rotation causes the shell to act after the manner oi a gyroscope, and so keep its head In the direction of its flight. Otherwise it would tumble over end for end, and loss of ranging power and inaccuracy would be the inevitable result. 11 the weight oi the cylindrical shell is 14001b., the weight of a spherical projectile of the same diameter would be very much less. Tke diameters being the same, the ranging powers oi the two projectiles are principally dependent upon their weight