When the trigger catch of a tumbler is broken or is worn away, it can be entirely removed by filing and a piece of steel fitted or held by a small rivet and then brazed. After being finished up and fitted to the trigger, the tumbler can be hardened, care being taken not to heat it sufficiently to melt the brazing material.
Describing Lines on Bright Surfaces.—Many gunsmiths find it difficult to make the pattern of work upon iron or steel, especially after the surface is finished. Yet it is necessary to have the outline of the intended form. For instance, if the pattern of a hammer for a revolver or a gun hammer, the sides of which are both flat (in fact the hammers of many breech-loading rifles are made in this manner), be required to be made on a piece of iron or steel that has been faced down, the method is to drill a hole for the screw or pin on which it turns, then fasten the pattern to the work by driving a piece of wire into the hole, and, with a sharp scriber, mark around the pattern, which is then removed and the work filed away to the line. If the hammer be a broken one, then care must be taken to have the pieces held carefully as they were before being broken. If the pieces be somewhat small and difficult to hold properly, warm them over a spirit lamp and smear the sides to be put against the blank, lightly with beeswax, and this will tend to hold them better in place and prevent their slipping.
To obtain a more permanent line and one that will show very distinctly in all its tracings, coat the surface on which the line is to be made with a film of copper. To do this take a lump of sulphate of copper, sometimes called blue vitriol or blue stone, wet it with water and rub over the bright surface of the work. The moisture will dry in a few minutes, leaving a surface or film of pure copper. Put the pattern in place and describe the outline. Upon removing the pattern the line will be found to be clear and showing very distinctly through the coppery surface. Three or four light rubs with the sulphate are sufficient to produce this surface, which is so very thin that it may be easily removed when the work is done with a fine file, or by rubbing with a bit of emery paper or emery cloth.
CHAPTER XXXIII.
ON POWDER AND SHOT.
To Select Buck Shot.—The proper way is to put a wad in the muzzle of the gun, about half an inch down, and fit the shot in perfect layers; if this is observed, there will be no necessity to try them in the cartridge case, as they will be sure to fit. Buck-shot cast from a mould with nine to the 1⅛ ounce, will just fit a twelve-bore barrel at the muzzle in a choke bore. If smaller shot is required, choose four to a layer, or five, and avoid the sizes that come between. At forty yards, all these pellets ought to go in a 26-inch circle, and the penetration be equal to a small rifle.
Weighing Powder, etc.—For weighing powder charges for rifles, Apothecaries’ scales and the Apothecaries’ table of weights and measures are used. The table is:
| 20 grains, | 1 scruple; |
| 3 scruples, | 1 drachm; |
| 8 drachms, | 1 ounce; |
| 12 ounces, | 1 pound. |
Powder is bought and sold by Avoirdupois weight, which has 16 ounces to the pound. The table is:
| 16 drachms, | 1 ounce; |
| 16 ounces, | 1 pound. |