THE MANFACTURE OF A RIFLEBARREL.

New Zealand Mail, Issue 1798, 22 August 1906, Page 14

THE MANFACTURE OF A RIFLEBARREL.

It is wonderful what strides have been made in the manufacture of the rifle since the invention of gunpowder. Place an old flint-lock by the side of the modern Lee-Metfocrd, or MartmiHenry, and compare the two. What a difference! One a rough, rugged-look-ing weapon, covered with curious inlaid scroll-work, maybe, and the owner, perhaps, the only man able to discharge it, on account of its many eccentricities; the other, a plain, smart-looking Aveapon, able to be fired with the greatest Precision—and to kill at a mile —by anybody with a pretence to being a marksman. The tivo appear to be as ill-assort-ed a couple as would be an old country yeoman of last century and a modem man about toAvn. It would be impossible in an article of this length to even briefly run through the history of rifles and riflemaking, for to do so Avould more than fill an ordinary-size J volume. The Royal Small Arms Factory is, perhaps, one of the largest places of its kind in the country. Six large buildings, literally teeming Avith machinery, constitute the factory and repairing department.. The A'isitor is beAvildered by the multiplicity of machines, all actuated from one source, and the miles upon miles of belting Avhich work the lathes, at which the different parte of the rifle are made. The steel body of the rifle itself, whicn, starting on its eventful career in the smithy, is at last hardened by being dipped in a bath of oil, goes through 150 operations alone. The foresight, backsight, trigger, magazine, and all other metal components have their origin here.

But. it is the barrel-making Avhich lias the greatest fascination for a visitor. He sees lying in heaps long rough bars oi steel, Aviiich, after an exceedingly eventful journey through the different parts of the workshop, finally make their appearance as the long blue-lookmg rifle barrels Avhich Avill, perhaps, be responsible for the destruction of many scores of human lives. The cylinders of rolled steel are purchased irom the contractors in short lengths, and the chief work of the smiths consists in heating and lengthening them. The change to the finished article is, of course, very gradual. After being lengthened in the smithy, these barrels are bored, and for this purpose are fixed in a lathe and drilled from each end of the bar. They are now approximately near the required gauge for rifling, and any further metal is iemoved by means of emery and Avater. Following this, a very delicate test is applied. The operator holds the barrel in an upright position, closes the lower end, and then places a cylindrical piece of metal inside the top end, Avhich the compressed air in the tube should support. On removing the top, or plug, the gauge should at once drop through. The size of bore being satisfactory, the next test of the barrel is for straightness,, and this test is always applied prior to rifling the bore. The barrel is held at an angle and supported by a stand, Avhich enables the man to see the- liglit reflected through it in perfect ringjs, provided the bore is absolutely straight. But the “viewer’s” subsequent test is more critical still, and is so trustworthy, that in a total length of 30.197iu. he is able to judg'c of a deflection of 1000th of an inch by causing the barrel to rotate in a lathe furnished Avith a dial indicator at the end. This dial is so finely marked that it can only be read by the aid of a magnifying glass. In a barrel so tested, Aviiich was the 4000th of an inch out, two smart blows Avith a hammer on the right spot completely straightened it.

Now the lifter takes the barrel under his special care. He uses what is undoubtedly the most intricate and yet most perfect piece of machinery in the place. The depth of rifling is only .005 of an inch, and" there are seven grooves, which the cutting tool produces after traversing the barrel forty-two times, or six times for each groove. The barrel remains fixed in the lathe, whilst the cutting tool worms its way through it, making one complete turn in every lOin, and removing each time but a very small amount of metal, yet extracting it in one unbroken piece, in appearance like a spiral spring. It is the backward movement of the cutting tool that rifles. When six cuttings have made one groove of the necessary depth the barrel, is turned in the lathe one-seventh of its diameter, and so on in succession till the whole seven grooves are formed. It is now “rifled." Then the barrel goes to the proving house, where it undergoes severe tests of its strength and accuracy and when found up to the required standard Is stamped and passed on to the assembling department.—“ Navy and Army."