The great strides made in the manufacture and forging of steel during the past quarter of a century, the improved tempering and annealing processes have resulted in the turning out of big guns solely composed of steel.
The various forms of modern ordnance are classified and named according to size and weight, kind of projectiles used and their velocities; angle of elevation at which they are fired; use; and mode of operation.
The guns known as breechloading rifles are from three inches to fourteen inches in calibre, that is, across the bore, and in length from twelve to over sixty feet. They weigh from one ton to fifty tons.
They fire solid shot or shells weighing up to eleven hundred pounds at high velocities, from twenty-three to twenty-five hundred feet per second. They can penetrate steel armor to a depth of fifteen to twenty inches at 2,000 yards distance.
Rapid fire guns are those in which the operation of opening and closing the breech is performed by a single motion of a lever actuated by the hand, and in which the explosive used is closed in a metallic case. These guns are made in various forms and are operated by several different systems of breech mechanism generally named after their respective inventors. The Vickers-Maxim and the Nordenfeldt are the best known in America. A new type of the Vickers-Maxim was introduced in 1897 in which a quick working breech mechanism automatically ejects the primer and draws up the loading tray into position as the breech is opened. This type was quickly adopted by the United States Navy and materially increased the speed of fire in all calibres.
What are known as machine guns are rapid fire guns in which the speed of firing is such that it is practically continuous. The best known make is the famous Gatling gun invented by Dr. R. J. Gatling of Indianapolis in 1860. This gun consists of ten parallel barrels grouped around and secured firmly to a main central shaft to which is also attached the grooved cartridge carrier and the lock cylinder. Each barrel is provided with its own lock or firing mechanism, independent of the other, but all of them revolve simultaneously with the barrels, carrier and inner breech when the gun is in operation. In firing, one end of the feed case containing the cartridges is placed in the hopper on top and the operating crank is turned. The cartridges drop one by one into the grooves of the carrier and are loaded and fired by the forward motion of the locks, which also closes the breech while the backward motion extracts and expels the empty shells. In its present state of efficiency the Gatling gun fires at the rate of 1,200 shots per minute, a speed, by separate discharges, not equaled by any other gun.
Much larger guns were constructed in times past than are being built now. In 1880 the English made guns weighing from 100 to 120 tons, from 18 to 20 inches bore and which fired projectiles weighing over 2,000 pounds at a velocity of almost 1,700 feet per second. At the same time the United States fashioned a monster rifle of 127 tons which had a bore of sixteen inches and fired a projectile of 2,400 pounds with a velocity of 2,300 feet per second.
The largest guns ever placed on board ship were the Armstrong one- hundred-and-ten-ton guns of the English battleships, Sanspareil, Benbow and Victoria. They were sixteen and one-fourth inch calibre. The newest battleships of England, the Dreadnought and the Temeraire, are equipped with fourteen-inch guns, but they are not one- half so heavy as the old guns. Many experts in naval ordnance think it a mistake to have guns over twelve inch bore, basing their belief on the experience of the past which showed that guns of a less calibre carrying smaller shells did more effective work than the big bore guns with larger projectiles.
The two titanic war-vessels now in course of construction for the United States Navy will each carry a battery of ten fourteen-inch rifles, which will be the most powerful weapons ever constructed and will greatly exceed in range and hitting power the twelve-inch guns of the Delaware or North Dakota. Each of the new rifles will weigh over sixty-three tons, the projectiles will each weigh 1,400 pounds and the powder charge will be 450 pounds. At the moment of discharge each of these guns will exert a muzzle energy of 65,600 foot tons, which simply means that the energy will be so great that it could raise 65,600 tons a foot from the ground. The fourteen-hundred-pound projectiles shall be propelled through the air at the rate of half a mile a second. It will be plainly seen that the metal of the guns must be of enormous resistance to withstand such a force. The designers have taken this into full consideration and will see to it that the powder chamber in which the explosion takes place as well as the breech lock on which the shock is exerted is of steel so wrought and tempered as to withstand the terrific strain. At the moment of detonation the shock will be about equal to that of a heavy engine and a train of Pullman coaches running at seventy miles an hour, smashing into a stone wall. On leaving the muzzle of the gun the shell will have an energy equivalent to that of a train of cars weighing 580 tons and running at sixty miles an hour. Such energy will be sufficient to send the projectile through twenty-two and a half inches of the hardest of steel armour at the muzzle, while at a range of 3,000 yards, the projectile moving at the rate of 2,235 feet per second will pierce eighteen and a half inches of steel armor at normal impact. The velocity of the projectile leaving the gun will be 2,600 feet per second, a speed which if maintained would carry it around the world in less than fifteen hours.
Each of the mammoth guns will be a trifle over fifty-three feet in length and the estimated cost of each will be $85,000. Judging from the performance of the twelve-inch guns it is figured that these greater weapons should be able to deliver three shots a minute. If all ten guns of either of the projected Dreadnoughts should be brought into action at one time and maintain the three shot rapidity for one hour, the cost of the ammunition expended in that hour would reach the enormous sum of $2,520,000.