Breeching taps should be made in pairs, one tapered a little and its mate made straight and with a full thread, so as to cut full at the bottom where the thread terminates. If the first tap be not tapered a little, the thread should be nearly all removed at the end, and gradually increased for five or six threads, when it will be of full size. A stem or projection is made as shown in the cut, Fig. 36, which enters and fills the bore of the gun and so serves to insure a thread straight with the barrel. If the bore be larger than the extension, slip over it a piece of brass tube or a ferrule of some kind, until it fits a little snug in the bore. If but little be wanting to make the fit, a piece of writing paper or a bit of card may be wrapped around it. Old-fashioned gunsmiths have been known to wind tow around an extension to make a fit. [Illustration: FIGURE 37.] The diameter of these extensions must be that of the smallest bored gun in which they will be used. The extension of the shot-gun tap may be about half-inch diameter. The length of the extension may be about an inch for rifles and an inch and a quarter for shot guns, the thread about an inch in length. The whole length of rifle taps may be about three and a half inches, for shot-guns about four inches. _Breech Pin Formers._—These tools are made of steel and have holes drilled through them and cutting teeth formed on one end (as shown in Fig. 37). In use it may be held stationary, and the breech-pin turned in the hole until the teeth form it to size and remove enough in length for the screw to be cut on the pin. Eight teeth are enough for the smaller sizes of these tools. If made with more teeth they are consequently finer and shallower and do not operate so well, or cannot be ground to an edge or sharpened with an oil stone if they become dull. The sizes must correspond with the size of the breech taps, or a little less than this size, as the dies used in cutting generally “raise” a thread a little larger than the work. The length of these tools may be about three-fourths of an inch or an inch, as may be best to make them. In use they can be held in a lathe chuck and the pin presented to them while running, or the operation may be reversed, the pin being rotated and the cutter held stationary. If to be used by hand, hold them in a vise or clamp, or make a fixture to hold the pin, using a bit-stock for turning them for cutting. The advantage of these tools is that the work is done quick, the body of the pin is of the same diameter, and the shoulder where it abuts against the barrel is true with the body; using a file for the work, it is difficult to produce these requirements. CHAPTER XVIII. TOOLS FOR CHAMBERING BREECH-LOADING BARRELS.