Part 5

Breech-loaders were hardly new. King Henry VIII of England, he of the many wives, had a match-lock arquebus of this type dated 1537. Henry IV of France even invented one for his army, and others worked a little on the idea from time to time. But it wasn’t until fixed ammunition came into use that the breech-loader really came to stay--and that was only the other day. You remember that the Civil War began with muzzle-loaders and ended with breech-loaders.

[Illustration: ASSEMBLING AUTO SHOTGUNS]

[Illustration: SOME OF THE SHOOTING TESTS]

Houiller, the French gunsmith, hit on the great idea of the cartridge. If you were going to use powder, ball and percussion primer to get your game, why not put them all into a neat, handy, gas-tight case?

THE FIRST AMERICAN MADE GUNS

~HOW THE FIRST AMERICAN GUN WAS MADE~

Two men, a smith and his son, both named Eliphalet Remington, in 1816, were working busily one day at their forge in beautiful Ilion Gorge, when, so tradition says, the son asked his father for money to buy a rifle, and met with a refusal. The request was natural for the surrounding hills were full of game. The father must have had his own reasons for refusing, but it started the manufacture of guns in America.

Eliphalet, Jr., closed his firm jaws tightly, and began collecting scrap iron on his own account. This he welded skillfully into a gun-barrel, walked fifteen miles to Utica to have it rifled, and finally had a weapon of which he might well be proud.

[Illustration: TYPES OF CARTRIDGES]

In reality, it was such a very good gun that soon the neighbors ordered others like it, and before long the Remington forge found itself hard at work to meet the increasing demand. Several times each week the stalwart young manufacturer packed a load of gun-barrels upon his back, and tramped all the way to Utica where a gunsmith rifled and finished them. At this time there were no real gun-factories in America, although gunsmiths were located in most of the larger towns. All gun-barrels were imported from England or Europe.

A VISIT TO A CARTRIDGE FACTORY

~HOW AMMUNITION IS MADE~

One of the first shocks you get when you start your visit through a cartridge factory is the matter-of-fact way in which the operatives, girls in many cases, handle the most terrible compounds. We stop, for example, where they are making primers to go in the head of your loaded shell, in order that it may not miss fire when the bunch of quail whirrs suddenly into the air from the sheltering grasses. That grayish pasty mass is wet fulminate of mercury. Suppose it should dry a trifle too rapidly. It would be the last thing you ever did suppose, for there is force enough in that double handful to blow its surroundings into fragments. You edge away a little, and no wonder, but the girl who handles it shows no fear as she deftly but carefully presses it into moulds which separate it into the proper sizes for primers. She knows that in its present moist condition it cannot explode.

[Illustration: INSPECTING METALLIC SHELLS]

[Illustration: EXAMINING PAPER SHELLS]

[Illustration: WEIGHING BULLETS]

Or, perhaps, we may be watching one of the many loading machines. There is a certain suggestiveness in the way the machines are separated by partitions. The man in charge takes a small carrier of powder from a case in the outside wall and shuts the door, then carefully empties it into the reservoir of his machine, and watches alertly while it packs the proper portions into the waiting shells. He looks like a careful man, and needs to be. You do not stand too close.

[Illustration: SHOOTING ROOM OF BALLISTICS DEPARTMENT]

[Illustration: CHRONOGRAPH FOR MEASURING]

The empty carrier then passes through a little door at the side of the building, and drops into the yawning mouth of an automatic tube. In the twinkling of an eye it appears in front of the operator in one of the distributing stations, where it is refilled, and returned to its proper loading machine, in order to keep the machine going at a perfectly uniform rate; while at the same time it allows but a minimum amount of powder to remain in the building at any moment. Each machine has but just sufficient powder in its hopper to run until a new supply can reach it. Greater precaution than this cannot be imagined, illustrating as it does that no effort has been spared to protect the lives of the operators.

[Illustration: PUTTING METAL HEADS ON PAPER SHOT SHELLS]

It is remarkable that, in an output of something like four million per day, every cartridge is perfect.

Such things are not accidental. The secret is, inspection.

~TESTING MATERIALS AND PRODUCTS~

Let us see what that means. It means laboratory tests to start with. Here are brought many samples of the body paper, wad paper, metals, waterproofing mixture, fulminate of mercury, sulphur, chlorate of potash, antimony sulphide, powder, wax, and other ingredients, and even the operating materials such as coal, grease, oil, and soaps. In the laboratory we see expert chemists and metallurgists with their test-tubes, scales, Bunsen burners, retorts, tensile machines, microscopes, and other scientific looking apparatus, busily hunting for defects.

For example, one marker is examining a supply of cupro-nickel, such as is used in jacketing certain bullets. A corner of each strip is first bent over at right angles, then back in the other direction until it is doubled, then straightened. It does not show the slightest sign of breaking or cracking, in spite of the severe treatment, therefore it is perfect. Let but the least flaw appear, and the shipment is rejected.

[Illustration: WHAT A SHOT TOWER LOOKS LIKE

SHOT TOWER--TALLEST BUILDING IN CONNECTICUT]

[Illustration:

LARGEST CARTRIDGE EQUALS MORE THAN 1,000,000 OF SMALLEST (HELD ON HAND)]

Two large iron cylinders descend in the center, coming down through the ceiling from above; we are invited to look through an open port in one of these.

We see nothing but the whitened opposite wall, against which a light burns.

It appears absolutely empty, though within it is raining such a swift shower of invisible metal that if we were to stretch our hands into the apparently vacant space they would be torn from our arms.

A large water tank below is churned into foam with the impact of the falling shot, and as we look downward we make out finally the haze of motion. It is so interesting that we take the elevator and rise ten stories to the source of the shower.

Here high in the air are the large caldrons where many pigs of lead, with the proper alloy, are melted into a sort of metallic soup. This is fed into small compartments containing sieves or screens, through the meshes of which the shining drops appear and then plunge swiftly downward.

But this only begins the process. Taken from the water tanks and hoisted up again, the shot pellets, in a second journey down, through complicated devices, are sorted, tumbled, polished, graded, coated with graphite, and finally stored.

The pictures shown in this story were prepared especially to illustrate this story of “How Man Learned to Shoot” by the Searchlight Library for the Remington Arms Company.

[Illustration: FORGING A MONSTER GUN

Photo by Bethlehem Steel Co.

This photograph shows gun ingots after being “stripped” and “cored.”]

[Illustration:

Photo by Bethlehem Steel Co.

This photograph shows a gun ingot in the process of being forged under forging press.]

[Illustration:

Photo by Bethlehem Steel Co.

This photograph shows a gun being fired at the Proving Grounds for test.]

The Parts of a Big Gun

~THINGS TO KNOW ABOUT A BIG GUN~

Before going into a description of the manufacture of a big gun it would be well to understand the following definitions:

The “breech” of a gun is its rear-end, or that end into which the projectile and powder charge are loaded.

The “muzzle” of a gun is its forward end.

By “calibre” is meant the inside diameter of the gun in inches. A 5-inch gun is one of “minor calibre,” and one of 14-inches a gun of “major calibre.”

The length of a gun is never expressed in inches or feet, but in the _number of times_ that its calibre is divisible into its length; thus, when we say a 12-inch 50-calibre gun, we mean a gun of 12 inches in diameter, and 12 times 50, or 600 inches long.

The “bore” is the hole extending through the center of the gun, from the rear face of the liner to its forward end.

The “powder chamber” is the rear part of the bore, and extends from the face of the breech plug when closed to the point where the “rifling” begins. The powder chamber is slightly larger in diameter than the rest of the bore.

The “rifling” is the name given to the spiral grooves which are cut into the surface of the bore of the gun, and give to the projectile its rotary motion when the gun is fired.

With the advent of “iron-clads” and heavily armored fortresses, it became necessary to increase the power of the guns in use, until to-day a 14-inch gun of 45 calibres fires a projectile weighing 1400 pounds, with an initial velocity of 2600 feet per second. An idea of this initial velocity may be better obtained by comparison when you realize that a train going sixty miles an hour is only traveling at the rate of 88 feet per second. Now, in order to produce such wonderful power in a gun, great pressure must be generated in the bore, and it was soon found that a one-piece gun, whether cast or forged, could not withstand such pressures.

To begin with, we may consider this one-piece gun, or any gun, as a tube which must withstand a great pressure from within, so that when a gun is designed care must be taken to see that the material from which it is constructed is strong enough to withstand this pressure. And not only must the gun be sufficiently strong, but it must not be too heavy, so that you see you cannot go on forever increasing the thickness of the walls of this tube. Besides, it is generally acknowledged that a simple tube or cylinder cannot be made with walls of sufficient thickness to withstand from within a _continued_ pressure per square inch greater than the tenacity of a square-inch bar of the same material; in other words, if the tensile strength of a metal is only twelve tons per square inch, no gun of that metal, however thick its walls, could withstand a pressure of twenty tons per square inch, and the modern big guns are tested at that great a pressure. And if we look further into this matter of pressures we find that when a gun is fired the pressure exerts itself in two ways; it tends to burst the gun longitudinally or down the middle, and it tends to pull the gun apart in the direction of its length. Of course, some method of strengthening this one-piece gun was sought after, with the result that to-day guns are either “_built-up_” or “_wire-wound_.”

A “built-up” gun is one made of several layers, each layer being separately constructed and then assembled together. The order of assemblage differs somewhat with the different calibres, but the method of assemblage is essentially the same, that is, the outside layers are heated and shrunk on the inner ones. This question will be treated at greater length later on.

A “wire-wound” gun is one in which the necessary additional strength is obtained by winding wire around an inner tube of steel, each layer being wound with a different tension of the wire; this type of gun has found great favor with foreign manufacturers. In this country, however, the “built-up” system is used almost exclusively, and so this description will deal with the manufacture of a “built-up” gun.

[Illustration: HOW A BIG GUN WOULD LOOK IF YOU WERE TO CUT IT IN TWO

Sketch Showing Construction of a Modern “Built-up” Gun.

_A_, HOOP; _B_, HOOP; _C_, JACKET; _D_, TUBE; _E_, LINER; _F_, HOOP.]

A modern “built-up” gun is composed of a _liner_, a _tube_, a _jacket_ and _hoops_.

The _liner_ is in one piece and extends the entire length of the bore and carries the “rifling” and the powder chamber.

The _tube_ is in one piece and envelops the liner for its entire length. Formerly the _tube_ carried the “rifling” and powder chamber, but due to the wearing out of the “rifling” with constant firing, a liner was decided on, so that now when the “rifling” becomes worn, the liner can be removed and a new one substituted.

The _jacket_ is usually in two pieces and is shrunk on the tube; it extends the entire length, and its rear end is threaded in the inside for the attachment of the “breech bushing.”

_Hoops_ are shrunk on over the jacket and in a big gun are sometimes as many as six or seven in number.

The liner, tube, jacket and hoops are made of the finest quality of open hearth steel, and the steel must conform to specifications set by the government.

[Illustration:

Photo by Bethlehem Steel Co.

This photograph shows a mould for a gun ingot under hydraulic press for fluid compression.]

The chemical composition having been determined, the necessary elements are weighed out and the whole charged into an open hearth furnace. When the furnace is ready to be tapped the molten metal is run into a large ladle, which in turn is taken by a crane to the casting pit, where the mould is filled. The ingots for the large calibre guns run from 42-inch to 48-inch in diameter, and after being poured they are immediately run under a hydraulic press, where they are subjected to a pressure of about six tons per square inch to drive out the gases, and then lowered to about 1500 pounds pressure per square inch for a certain length of time during the cooling. This pressure tends to make the ingot solid, by expelling the gases, which would cause blow-holes, and by preventing “piping” and “segregation.” When a metal cools, the top and sides cool first, and this outer layer shrinks and pulls away from the centre, with the result that a cavity or “pipe” would be formed, but the hydraulic pressure forces fluid metal into this cavity and so prevents the “pipe.” The cooling also causes the various elements to solidify separately, and they tend to break away from the mass and collect at the centre; this is called “segregation,” and is also

## partially prevented by fluid compression. A solid ingot, however, is

obtained, and this is absolutely necessary.

After the ingot has cooled sufficiently it is “_stripped_,” that is, it is removed from the mould, and then it is sent to the shop to have the “discard,” or extra length, cut off. When the ingot is cast, an extra amount of metal is poured into the mould to permit this discard, the theory being that the poorer metal, together with gases and other impurities, rise to the top. The government specifications require that there shall be a 20% discard from the upper end and a 3% discard from the lower end. The discard having been cut off, the ingot is “cored,” that is, its centre is bored out, the diameter of the hole depending on the size of the ingot.

[Illustration: TAKING THE BORE OF A BIG GUN

Photo by Bethlehem Steel Co.

This photograph shows gun ingot in boring mill being cored.]

The ingot is now ready for the “forge,” and on its receipt in the forge shop it is placed in a furnace to be heated; and here great care must be exercised to prevent setting up any additional strains in the ingot. When the ingot was cooling just after casting the metal tended to flow from the centre; the interior is still in a condition of strain, and if the cold ingot is now placed in a hot furnace, cracks are apt to form in the centre, causing the forging to later break in service.

However, the ingot having been properly heated, it is ready for either the forging hammer or the press. The present-day practice, though, is to forge the ingot under a press forge, as the working of the metal causes a certain flow, and as a certain amount of time is necessary for this flow, the continued pressure and slow motion of the press allows the molecules of the metal to adjust themselves more easily, and a better and more homogeneous forged ingot is produced than if the forging had been done with a hammer.

When forging a hollow ingot, a mandrel, merely a cylindrical steel shaft, is placed through the hole in the ingot and the ingot forged on the mandrel, thereby not only is the outside diameter of the ingot decreased, but the length of the ingot is increased. The usual practice is to continue the forging until the original thickness of the walls of the ingot is decreased one-half and until the ingot is within two inches of the required finished diameters. The ingot is now known as a “forging,” and the lower end of each ingot as cast will be the breech end of the forging that is made from it.

The next process is that of “annealing.” This consists in heating the forging to a red heat and then allowing it to cool very slowly, and is usually done by hauling the fires in the furnace after the correct temperature has been attained and permitting both to cool off together. This process is to relieve the strains set up in the metal during forging, and further, it alters the molecular condition of the steel, making a finer and more homogeneous forging.

[Illustration: HOW THE GUN TUBE IS TEMPERED

Photo by Bethlehem Steel Co.

This photograph shows a gun tube ready to be lowered into oil bath for “oil tempering.”]

After annealing, the forging is ready to go to the machine shop to be rough bored and turned. The forging is set in a lathe, the breech end being held by jaws on the face-plate and the muzzle end by a “pot-centre,” a large iron ring having several radial arms screwed through it. The lathe can now be turned and the forging centered by screwing in or out on the jaws of the face-plate or the radial arms of the “pot-centre.” When centered, several surfaces are turned on the forging for “steady rests” and then all is in readiness for the turning and boring.

In both operations of “turning” and “boring,” the work revolves while the cutting tools are fed along. Turning is very simple and usually several tools are cutting at the same time, but boring is a more delicate operation, because the workman cannot see what he is doing. And in boring, either a “hog bit” or a “packed bit” is used; a “hog bit” is a half cylinder of cast iron fitted with one cutting tool and used for rough cuts, while a “packed bit” is a full cylinder of wood with metal framing and carrying two tools 180° apart and used for finishing cuts.

The forging, having been rough machined, is now ready to receive its heat treatment in order to give to the steel its required physical characteristics. Every piece of steel used in gun manufacture must conform to certain specifications as regard both its physical and chemical characteristics. The chemical analysis was made at the time the ingot was cast; now for the treatment of the forging, prior to the physical test as to its tensile strength, elastic limit, elongation and contraction.

The “tensile strength” of a metal is the unit-stress required to break that metal into parts. If a round bar ten inches in cross-section area will fracture under a strain of 120 tons, its tensile strength is 120 ÷ 10 or 12 tons per square inch. Tensile strength is usually expressed in pounds per square inch.

The “elastic limit” of a metal is the unit-stress required to first produce a permanent deformation of the metal. If a bar of metal be subjected to an increasing strain, up to a certain point that metal will be perfectly elastic, resuming its normal shape when the strain is removed; at the first permanent set or deformation, however, the elastic limit of that metal has been reached. Elastic limit is expressed in pounds per square inch.

By “elongation” is meant the increase in length in a bar when its tensile strength is reached. If a bar 10 inches long after rupture measures 11.8 inches, its elongation is 18%.

By “contraction” is meant the decrease in cross-section area in a bar when its tensile strength is reached. If a bar 1 square inch in area after rupture is only .75 of a square inch in area, its contraction is 25%.

These definitions being understood, a brief description of the heat treatment can be taken up, because it is after this treatment that standard bars are taken from the forgings to undergo the physical tests. The first step consists in “tempering” or hardening the metal. The piece to be tempered is placed in an upright position in a high furnace and uniformly heated to the required temperature. It is then lifted from the furnace through an opening in the top and carried by a crane to an oil tank of suitable depth and plunged into the oil. This rapid cooling or “tempering in oil” is facilitated by having the oil tank surrounded by a water bath, so arranged that a supply of cold water is constantly in circulation to carry the heat from the mass as quickly as possible. This operation produces exceeding toughness, increases the tensile strength and raises the elastic limit of the metal.

Now the forging is again annealed, so as to relieve any strains set up by tempering and to soften up the metal to the degree required by the specifications. It also increases materially the elongation and contraction. Great care must be exercised in the heat treatment, as the acceptance or rejection of the forging depends upon whether or not the test bars pass the required specifications.

The forging is now submitted for test and the test bars taken. In the manufacture of a big gun, four test bars are taken from the breech end and four from the muzzle end of each forging and these bars sent to the physical laboratory. Quite an elaborate testing machine is provided, and if the bars pass the required tests the forging is accepted and is sent to the machine shop for finish-boring and turning.

~SEARCHING FOR POSSIBLE DEFECTS~

Frequently during finish-boring the work is examined to see that the bit is running true, and great care must be exercised to prevent its running out of alignment.

After finish-boring every forging is “bore-searched,” that is, the bore is carefully examined for any cracks, flaws, streaks or discoloration. A special instrument called a “bore-searcher” is used and consists of a long wooden handle which has a mirror inclined at 45° at one end, together with a light to illuminate the bore, and so shielded as to obscure the light from the observer. (See sketch.)

[Illustration]

The bore is also inspected by the foreman after each boring, but the final “bore-searching” is done by an inspector.