Shot Gun Ammunition
( Originally Published Early 1900's )
Powders-In treating of ammunition, gun-powder naturally occupies the premier position. Black powder for shot guns, if not indeed already obsolete, probably will soon be entirely superseded by the more modern forms of ex-plosive, except perhaps in very hot climates, and there is therefore no necessity to investigate that particular part of the subject. There are many well-tried smokeless powders on the market for the sportsman to choose from, and fresh ones are constantly being brought to his notice. The earliest form of smokeless powder was designed to occupy, power for power, the same space in the cartridge-case as did black powder. Powders of this type have done excellent work in their time, but they leave a good deal of solid residue after combustion, which, when shooting against wind, is frequently blown back into the eyes of the shooter. The newer form of concentrated powders are tolerably free from this defect, and most of them really deserve the application smokeless, which is more than can be said of the earlier kinds, and therefore they are gradually winning their way in public favour.
Nitric acid is the active agent in all smokeless powders at present in use. The principal absorbents are wood pulp, cotton wool, and glycerine. These substances, after treatment with the acid and combination with other ingredients, are so manipulated that the combustion is retarded to such extent as to insure that on explosion the pressure set up in the gun shall not exceed three tons per square inch, or about the pressure given by a full charge of black powder, which was taken as the standard of comparison. If it is desired to use smokeless powders in shot guns exceeding 10-bore, one of the primary types of powder first mentioned, which comprise Schultze, E.C., S.S. and Amberite, should be chosen for the reason that sufficient experience has not as yet been obtained to determine satisfactorily as to the action of the concentrated powders in guns of greater calibre.
Smokeless powder may be kept for any length of time without deterioration in a cool dry place, if the temperature is within from 40° to 6o° Fahr. In cold weather better results will be obtained if the cartridges are kept in, a warm room for a few hours before use, so as to bring their temperature up to about 60°.
There are two kinds of shot made; "soft," which is composed of nearly pure lead, and the so-called " chilled," which is in reality an alloy, with lead as the principal ingredient. Chilled shot possesses many advantages over the soft kind, for, as its name implies, the pellets are harder, and for this reason they do not lose to so great an extent their spherical form in the cartridge or bore of the gun, and in consequence of this they keep a more correct line of flight. The pellets are formed by pouring the molten metal through a perforated plate fixed at the top of a high tower. The height of the drop gives time for the naturally-formed globules of metal to harden before falling into a tank of water, which is placed in the base of the tower to receive them. The larger sizes of shot are generally used for wild fowl, against the strong feathers and tough bodies of which they are very effective, often at ranges exceeding one hundred yards. The choice of size of shot is usually regulated by the size of the game and the distance at which it is to be killed. No. 6, of 270 pellets to the ounce, is the size most generally used for ordinary purposes of game shooting in England.
Cartridge Cases-For shot guns these are sometimes made of solid drawn brass; but this more particularly applies to the larger sizes used for wild-fowling purposes. For guns of ordinaryliable to cut the fingers of the shooter. Several improvements have been made recently in the paper used in the manufacture of cartridge cases, the most important of these being the "Pegantoid" process, which renders the paper waterproof.
Concentrated powders require a special form of cartridge case, having the interior of the base, that is to say the powder chamber, of a conical shape. These bases vary somewhat in form for the several powders, as also do the cap domes, which have one or more flash-holes of various sizes. The fulminate in the percussion cap is somewhat different in composition and in action from that required to ignite the older type of smokeless powder. A question of vital importance bearing on the action and behaviour of present-day explosives is the inequality of power of the percussion caps, many serious accidents having resulted from this cause. In some instances, owing to the small quantity of fulminate in the cap, the shot charge has been moved only a very short distance up the barrel and the next charge fired has burst the gun. An excess of fulminate in the cap gives rise to high gas pressure in the breech, which is likely to injure the weapon, and in any case irregularities of the sort indicated are a barrier to good and regular work.
Wadding-In the shot cartridge the wad-ding is a very important item, as it must fulfil several requirements. It must act as an effectual gas check, not only at the instant of explosion but also while the charge is passing from the cartridge into the bore of the barrel, thus effectually bridging over that part of the bore of the gun termed the " cone."
From numberless experiments it has been found that in a 12-bore a card wad of medium thickness over the powder, next which is a 3/8 in. soft felt with a grey cloth under the shot, gives the best results ; the wad over the shot only being sufficiently stout to keep the pellets from shaking loose during transit.