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§ 60 explosive is not so called by reason of any greater total energy content, but rather on the effects of its rapidity of action; in brief, its power of detonation.

It is evident that, for the purpose under contemplation, the destruction of the less substantial structural parts of aeroplanes, etc., if we are able to secure the proper and immediate expansion of the bullet on impact without the use of an explosive charge, every useful purpose will be served. The bullet energy, even reduced to about one-quarter of its initial value by 1,000 yards flight, is more than sufficient, if definitely expended in the impact, to destroy any strut or spar or other light constructional part, without any aid from an explosive charge. The question is, whether the expansion of the bullet can be induced to take place with sufficient rapidity by any less drastic device.

§ 61. The Expanding Bullet. Any bullet is considered an expanding bullet if it be so made as to spread or mushroom on impact with its objective. But it is more usual to restrict the term to bullets having some special provision artificially to assist or facilitate their expansion, and, generally speaking, the objective is assumed to be game or other living quarry of some description. Evidently, if the target be hard enough, every bullet will expand to some degree. The means usually adopted in the case of the solid-lead bullet is to drill or form a hollow in the nose, as familiar to all who have used the sporting rifle. Another well-known method is to split the nose for a short distance by two cuts at right angles. In the case of the nickel-covered bullet the drilled nose again is sometimes adopted, or the nickel sheath at the nose, or point, of the bullet, is removed, the lead core being laid bare. All these devices have been practised in connection with sporting ammunition for many years. The art of designing an expanding