1. Wear.—(i) Wear in the bore of a rifle is due to three causes: (a) the friction of the bullet; (b) the heat generated when ammunition is fired; and (c) the friction of the pull-through gauze when the bore is being cleaned. When care is used in cleaning, 5,000 to 6,000 rounds can be fired from a rifle before it becomes unserviceable.
(ii) Undue Wear.—Undue wear is caused by improper and unnecessary use of the pull-through gauze, to prevent which it is most important that the instructions for cleaning be adhered to. It may be necessary to modify these instructions to suit local climatic conditions, or particular rifles which are in a bad state of preservation.
(iii) When a rifle barrel is new, the interior of the bore carries a high polish, and this is a great safeguard against rust and metallic fouling, but as the bore becomes worn, this polish will diminish. Efforts to restore it with wire gauze on the pull-through result in unnecessary wear. In a well-cared-for rifle, while the brilliancy of the polish will diminish, the lands of the bore should always be bright and free from all stain of rust or fouling.
2. Fouling.—(i) Fouling is of two kinds: (a) Internal, probably caused by the forcing of gas or harmful material into the pores of the metal; (b) Superficial, caused by the deposit in the bore of the solid products of combustion of the charge and of the cap composition. The result of neglect in either case is the formation of rust in the bore, and, as a consequence, corroded barrels, calling for the excessive use of wire gauze, or even more drastic treatment, thereby causing unnecessary wear.
(ii) Internal Fouling.—Internal fouling can be removed satisfactorily by the use of boiling water [Sec. 4, para. 6 (ii)]. If for any reason this method of cleaning cannot be used, the barrel will “sweat,” and a hard black crust of fouling will appear in the bore. This will turn to red rust if not removed, and the rifle will then require repeated cleaning with flannelette, and probably with gauze, for a time, which will vary according to climatic conditions and the state of the bore.
(iii) Superficial Fouling.—Superficial fouling is readily removed, when warm, by the use of a pull-through and flannelette, but if it is allowed to remain long in the barrel, it will become hard and will have a corrosive effect equal to that produced by internal fouling.
3. Nickelling.—The appearance of nickelling, or metallic fouling, should be watched for. It is caused by a portion of the cupro-nickel of the envelope of the bullet being left on the surface of the bore, and appears as a whitish streak on the lands, or as a slight roughness on the edge of the grooves. If it is deposited near the muzzle or the breech, it is visible to the eye when the bore is clean, but in the centre of the bore it can only be detected by the use of the gauge plug. It is a cause of inaccuracy, and if a rifle for no apparent reason shoots badly, its presence should be looked for as a possible explanation. The soldier will make no attempt to remove it himself, but will hand his rifle to the armourer, or other qualified person, to be cleaned.
Section 3.—Materials used for Cleaning Arms.
1. Pull-Through ([Fig. 1]).—(i) A pull-through fitted with a weight, and an oil-bottle to contain Russian petroleum, are carried in the recess in the butt of the rifle. The pull-through is made with three loops. The first—i.e., nearest the weight—is for the gauze when used; the second for the flannelette; the third is provided merely as a means of withdrawing the pull-through in case of a jamb. Neither flannelette nor gauze should be placed in this loop. When signs of wear appear, a new cord should be supplied, to avoid the risk of the pull-through breaking in the rifle. If a breakage does occur, the rifle must be at once taken to the armourer. No attempt should be made by the soldier to remove the obstruction.
(ii) Packing the Pull-Through.—The pull-through is packed above the oil-bottle as follows: Hold the pull-through (loop end) between the forefinger and thumb of the left hand, so that the end falls about 2 inches below the third finger; roll it loosely three times round the first three fingers. Slip the coil off the fingers, and lap it tightly with the remainder of the cord, leaving sufficient to allow the weight to drop easily into the recess in the butt. Push the cord into the trap, leaving the loop end uppermost, drop the weight into the recess, and drop the trap.