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of manufacture is nearly similar to that alluded to under Charcoal-iron.
In forging the iron into barrels the same principle is not adopted in all cases, some being twisted, while others of the commonest kind are joined longitudinally into a tube. Both these processes are now carried on only at Birmingham, London at present not containing a single forge for the purpose. The process of forging twisted barrels is as follows:- The rod after being heated is twisted into a spiral form by means of two iron bars, one fixed and the other loose. In the latter, which is turned by a winch-handle, there is a notch which receives the rod, and this being prevented from turning round with it by means of the fixed bar, is compelled to assume a spiral form. According to the breadth of the rod will be the quickness of the spiral, which varies froin that shown in the accompanying sketch, to the
BREADTH OF ROD IN BEST GUNS. (HALF SIZE.)
form given in the lowest quality of sham damn, or twopenny skelp, which are forged in bands of the following width, but which nevertheless are not bettered by this
BREADTH OF BOD IN COMMON GUNS. (HALF SIZE.)
twisting. When the rod is completely converted into this spiral form, it is removed and suffered to cool, while others are being bent the same way; and the next process is for the welders to join several of these together, and at the same
time weld the edges of the bent rods by the blow of the forge hammer at a white heat. The welder commences with a stout spiral of sufficient thickness for the breech ends, heats it to his mind, and then, removing it from the fire, gives the end a smart blow against the anvil, known by the technical term "jumping." This is repeated till the welding is complete, when a second portion is put into the fire, and the two ends being brought into contact so as to fit, which requires considerable practice, a "jump” on the anvil welds them together. By repeating this operation again and again the proper length for the barrel is obtained, and then the tube is made as perfect as possible at this stage by hammering it at a proper heat on a mandril, the external surface being made circular by placing it in a groove corresponding to its intended form. After this hammer-hardening by means of light hammers is adopted for the purpose of consolidating the texture of the iron, and then the twisted barrel is completely forged. For forging the plain barrel the smith takes two bars of iron, bends each of them over a mandril into rather more than a half circle; then heating them to a welding heat, he places both upon the mandril with their edges overlapping, and welds them together by repeated blows of his hammer.
The boring and grinding are effected by the person who is called the "barrel-maker," though certainly the smith might more properly be entitled to that appellation. Of these barrel-makers London contains several, and indeed every gunmaker would probably assert that he employs a workman of this class, though in many cases the same man works for several masters. It must be remembered that when forged the barrel is only a rough tube, the internal bore being smaller than it is intended to be when finished, and allowing of the removal of a considerable quantity of metal. The first thing to be done is to convert the interior into the nearest possible approximation to the form which it is intended to maintain permanently, and this is done by boring it with a machine called a “bit.” This instrument may either be used by the hand, when it is fixed in a stock and made to turn in the interior of the barrel, or it is placed in the spindle or “chuck” of a frame, which has also
carriage for the barrel to travel in, and is exactly similar in principle to a turner's lathe. The boring bit, being selected
a of a proper size, is placed in the centre of the spindle, ready to revolve as soon as the latter is set in motion; the barrel is then fixed in its carriage, so that it may gradually be pushed on upon the bit as the latter clears its way, and then the spindle is made to revolve by attaching its driving-wheel to the motive force, whether hand or steam. The bit is square for about twelve or fourteen inches, with four angles, two of which are ground sharp, while the other two in the finishing operation are kept from the interior of the barrel by a slip of wood, which diminishes the friction considerably. Water is constantly poured upon the barrel as the work goes on to keep it cool, and when the bit has cleared its way through, another, slightly larger in size, is introduced, till the barrel is of a proper bore. When the interior is finished it bears a fine polish, but it is a mere cylinder, and will still require some slight modification to make it shoot correctly ; but this is generally done by a hand bit. Next comes the grinding of the exterior, which is either done by means of large stones made to revolve with great velocity, and against which the workman holds the barrel, allowing it at the same time to turn round comparatively slowly in the hand; or a self-acting lathe is made to take the part of man and stone, and any number of barrels are then turned out exactly similar to each other in every respect but in the metal itself, which of course may and will vary slightly. The method by turning is the more true, but if care is not taken to keep the machinery in perfect order the tool is apt to tear up the surface and overheat the metal, which can be more completely avoided by the grindstone.
When the barrels are thus bored and ground, they have still to be put together if for a double-barrelled gun, and in any case to be breeched, cut to a proper length, and finally bored for shooting. In the first of these operations, considerable nicety is required in order to direct both barrels at the same object. It must be remembered that the breech-end is much thicker than the muzzle, and consequently in placing together two barrels as they come from the stone or lathe, if the two external surfaces touch at both ends, the
internal ones are not parallel. If, therefore, they were soldered together in this form, and shot from a fixed rest, the line of fire of the two would cross at a few yards from the muzzle, varying in distance according to the thickness of the breech. To avoid this objection, the iron of the opposite sides of each barrel is cut away until they approximate sufficiently, for an exact parallelism is to be avoided, because in shooting from the shoulder, the weight of the other barrel causes in each case a slight inclination in the opposite direction from the true axis. A rib of iron is introduced between and above the two barrels, and this is slightly elevated, to allow for the tendency to fall which shot has even at forty yards' distance. Mr. Greener is of opinion that this dropping of the shot is about twelve inches in forty yards, but it varies considerably in different guns, and according to the charge. This may, however, be taken as an approximation to the truth, but for all practical purposes any very exact calculation is useless, inasmuch as the shooting of guns will in great measure depend upon the proportion of powder to shot, and also in no slight degree upon the way in which they are “stocked.” Mr. Prince has proposed a plan for elevating one barrel slightly more than the other before brazing them together, so that one shall hit the mark exactly at 40 yards, and the other at 60. This seems likely to be of service for double guns, the objection that one barrel would be thereby more frequently used than the other, being met by the explanation that towards the end of the season long shots are the rule, and 40 yards the exception, and that "right and left” being then unusual, the more elevated barrel may be used for single shots. For pigeon-guns it is particularly applicable, and I think also for general shooting. When the two barrels and the rib are accurately fitted, they are soldered permanently together. The usual practice is to braze four or five inches with hard solder, but Mr. Greener shows the impropriety of this plan, inasmuch as it requires a white heat for its performance, which expands the iron again to the state in which it was prior to the cold-hammering. He asserts, and I believe with perfect truth, that soft-soldering, if properly done, is quite strong enough, and he declares that he never uses any other method, which, as his guns are well
known to be as strong as any others, is a sufficient guarantee of its efficiency.
The barrel or barrels having been brought to the condition of tubes open at each end, in order to complete them, it becomes necessary to close one of these by some means, which may be either a plug screwed in permanently, as in the percussion gun, or temporarily, as in the needle-gun and some other breech-loaders, or by some mechanical means keeping a block of iron in close apposition with the end of the barrels. These various methods must be described more minutely under the respective guns to which they belong.
AU shot-guns must now be proved twice before they can be sold, according to an Act passed in the year 1855. The first is called a "provisional proof," and is carried out when the barrel is in the rough, but the second requires that it or they shall be pretty nearly finished—that is to say, if a double gun, both barrels shall be soldered together, the breeches adapted, and the nipples screwed in. By this change in the method of proving, the trial is really a sufficient one, and I believe we shall hear of fewer guns bursting every year, as the old ones proved under the former régime become displaced from general use. Revolving arms are only proved once—that is, after they are made up, for as the barrel is not intended to contain the charge, it is not complete without the addition of the chamber. Breech-loading guns, not being revolvers, are tried provisionally as well as after they are completed. The penalties for forging proof-marks and for selling guns without them, are so heavy, that the offence, I believe, is rarely committed. According to Schedule B. of the “Gun-barrel Proof Act” of 1855, small arms are divided into five classes, as follows:
1st. Single barrelled military arms of smooth bore. 2nd. Double barrelled military arms of smooth bore, and all rifled arms whether double or single barrelled, not being revolvers or breech loaders.