It is here necessary to give a short account of the more common deformities met with, and to refer to the special characters possessed by different types of bullet of small calibre which may affect the ease with which deformity is produced, and the degree to which it is commonly carried. The effect of ricochet is to lower the velocity of flight, and at the same time to effect certain alterations of form in the bullet. These with rectangular impact in the case of bullets travelling at a low degree of velocity consist in a bending and deformation of the tip; in the higher degrees, of bending, shortening, extensive destruction, or complete fragmentation. If the bullet makes lateral impact, only widening and flattening result, often with the escape of the lead core from the mantle. That a ricochet bullet may travel a considerable distance is shown by the following observations quoted from Nimier and Laval.[10]
Fig. 26.—Sections of four Bullets to show relative shape and thickness of mantles.
From left to right: 1. Guedes; regular dome-shaped tip; mild steel mantle; thickness at tip 0.8 mm.; at sides of body 0.3 mm. 2. Lee-Metford; ogival tip; cupro-nickel mantle; thickness at tip 0.8 mm.; gradual decrease at sides to 0.4 mm. 3. Mauser; pointed dome tip, steel mantle plated with copper alloy; thickness at tip 0.8 mm.; gradual decrease at sides to 0.4 mm. 4. Krag-Jörgensen; ogival tip as in Lee-Metford; steel mantle plated with cupro-nickel; thickness at tip 0.6 mm.; gradual decrease at sides to 0.4 mm. The measurements of the sides are taken 2.5 cm. from the tip. Note the more gradual thinning in the Lee-Metford mantle.
Up to a distance of 1,700 to 1,800 metres the bullet may make several ricochet bounds. When the bullet strikes first at short distances (as 600 metres), it may make several bounds of from 300 to 400 metres: at moderate distances (as from 600 to 1,200 metres), bounds of 200 to 300 metres; and at distances above 1,200 metres, bounds of 100 to 200 metres. The length of the ricochet bounds depends on the angle of impact of the bullet with the ground, the nature of the slope of the latter, and the velocity of the bullet.
Putting aside the question of calibre and volume of the bullets we are concerned with, I believe the most important variations as serious effects of ricochet depend on the relative thickness and the composition of the mantles. Fig. 26 illustrates the relative thickness of the mantles in the Krag-Jörgensen, Mauser, Lee-Metford, and Guedes bullets. Given an equal degree of force and velocity on the part of the bullet at the moment of impact, the assumption is justifiable that the thinner mantles would tear or burst more readily in direct ratio to their relative thinness. I believe this assumption to be borne out by my own experience of the common deformities that occurred; but the great relative frequency with which Mauser bullets came under my observation, and the difficulty of forming any estimate of the velocity and force retained by any particular bullet at the moment of impact, make it impossible for me to express myself with the confidence which I should wish.
Fig. 27.—Normal Mauser Bullet
The second condition which influences the nature and degree of the deformities depends on the relative tenacity or brittleness peculiar to the metal employed in the manufacture of the mantles. In the case of the Lee-Metford this consists of an alloy of 80 parts of nickel with 20 of copper. The Krag-Jörgensen and Mauser are ensheathed in steel plated with cupro-nickel, and the Guedes has a plain steel envelope coated with wax.
Both as a result of experience in the field gained from ricochet bullets, and in the hospitals from bullets which had undergone deformation within the body, I am under the firm impression that the thin nickel-plated steel envelope of the Mauser bullet splits more readily than the thicker and more tenacious cupro-nickel envelope of the Lee-Metford, that the direction of the ruptures is more purely longitudinal, and the fissuring itself more extensive and complete.