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Page:Popular Science Monthly Volume 90.djvu/548

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�A Gun Without a "Kick"

��It fires a shell weighing from 12 to 14 pounds at a muzzle velocity of 1175 feet per second. The recoil action is overcome by discharging a charge of shot and vaseline from the rear

A BULLET in a gun, being lighter than the weapon, gives way first when the powder is fired, and travels faster; but the gun of which the breech-block is a part, travels the other way just the same. The nearer the weight of the gun is to the weight of the bullet or shell, the faster it travels, and the heavier, therefore, is the "kick" of the gun. In theory, if the gun were the same weight as the bullet they would fly in opposite directions at the same rate of speed.

' Now if you put a charge of powder in the middle of a gun barrel, and put a bullet of the same weight at one end of the charge as a bullet placed at the other end of the charge, then touch her off, the gun won't kick at all. The two bullets will merely go off in opposite directions. The expansive force of the gas has operated in both directions as usual, but there was nothing to move the gun itself. So much for a principle well known in gunnery for a hundred years.

The recoil of a cannon is taken up by cylinders of air or liquid precisely as the slam of the spring-impelled door is taken up by air cylinders. The barrel slides on ways under the back-

��It is based on the theory that action and reaction are equal and in opposite directions

By Edward C. Grossman

thrust of the gas, and its motion is checked by the cylinders and the perforated pistons within. Old types of guns ran back every shot, and the naval crews had to tail on to the tackle and run the gun back into battery after reloading, just as the field artillerymen used to run back their pets after each shot. This was slow, and neces- sitated resighting — termed "relaying" in gunnery parlance — for every shot. The use of recoil cylinders stopped all this.

Presently there arose the need for a bigger gun for aeroplane fighting, both for the other planes, and for the things of land and water the planes didn't like. Planes are cranky things so far as stability is con- cerned, and it was obvious that you couldn't have a gun kicking around in one of them without disturbing things. It was equally obvious that you couldn't put a two or three hundred-pound gun and recoil mechanism in a plane in which the last ounce of weight was figured, because that meant cutting down speed and raising plane area.

Then came the man who could apply a wellknown 'principle to a wellknown need. He is Commander Cleland Davis, U. S. N., Retired. If, he figured, a gun with a

���The throw of a lever rolls the rear barrel and exposes the breech end for the reception of the ammunition. Another throw of the lever returns the rear barrel to its former position and locks it

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