The only substitute to answer for this tool is to file down the jaws of a monkey wrench so that they will turn between the extensions of a patent breech while the first breech is being removed. This is a poor substitute, as there is only one handle to turn with, and when force is applied to remove the breech it does not have the force applied equally to each side as in the other kind of wrench, consequently it is not as effective nor so easy to remove the breech. If an extension to form another handle could be improvised it would make it much better. [Illustration: FIGURE 13.] _The Bit Stock._—Even if the gunsmith have a lathe there is much work that can be done to advantage with a common bit-stock. But as the drills and tools used in the lathe generally have round shanks by which to hold them in the chuck, the square hole where bits and tools are held in the bit stock must be filled by brazing or soldering a piece of iron into it and boring a hole to fit the shank of the lathe tools. It is advisable to have these shanks about seven-sixteenths diameter, as explained under the heading “Shanks of Tools.” In holding small drills made of steel wire or twist drills a small drill chuck must be fitted to the bit stock. A small solid chuck with a quarter inch hole may be made with a shank to fit the seven-sixteenth hole. A set screw must be fitted to hold the shanks of the two sizes mentioned. [Illustration: FIGURE 14.] _Bottoming Tools._—Bottoming tools are used for letting in locks, cutting out for escutcheons, and are useful in other places where a chisel cannot be made to operate. The form of this tool is shown in Fig. 14. It consists of a square or round shank about three-sixteenths or a quarter-inch in diameter and about six inches long. At one end a wooden handle is attached, and the other end is bent at an angle which is about half an inch or perhaps a little more, and on this angle is another one turned parallel with the shank and which is about three-eighths of an inch long. This is the cutting end and is fashioned like the cutting edge of a chisel, and is about a quarter of an inch wide. The bottom side, as it would be held for use, is ground flat and the upper side bevelled like a chisel. The cutting edge may be square or rounded to suit round places as letting in the bridle of a lock. The size given is that generally used, but if it be made about twice this size it will be found very useful in letting in octagon rifle barrels; if the tool be made larger and hollow like a gouge it is very useful in letting in round gun barrels. In letting in break off straps it will be found to take the place of a chisel to some advantage.