Some of the bullets used in this test were hollow-point. velocity for various calibres fired at water. This contact point will often have paint, wood fibres or Table 4.5 Critical angle vs. Bullets which have ricocheted from glass, steel, concrete or wood have a very distinctive flat spot which is characteristic of the material where the contact has been made. This tumbling gives rise to a distinctive whine or whirring noise as the tumbling bullet passes through the air.ĥ. Bullets will invariably lose their gyroscopic stability and tumble after ricocheting. This effect is illustrated by Table 4.5.Ĥ. The critical angle for a given bullet type/target medium is not velocity dependent. In this instance, it would appear that the collapsing hollow-point bullet nose increases the incidence angle, thus increasing the propensity for ricochet.ģ. The critical angle for a soft or hollow-point bullet is lower than that for an equivalent fully jacketed bullet. This equates to the bullet striking the surface at a greater incidence angle and therefore a greater ricochet angle.Ģ. It would appear that if sufficient cratering of the surface occurs on bullet impact, the exit plane of the crater will be of greater angle than the incidence angle. Table 4.4 Ricochet angle for 0.45 ACP FMJ bullet from various surfaces at various * Indicates severe cratering leading to variable results and, in some cases, disintegration of incident angle for various bullets on smooth concrete. In most cases of bullets ricocheting from a hard surface, the angle of ricochet is considerably less than the angle of incidence (Tables 4.3 and 4.4).Īs can be seen from the following tables, with hard-jacketed, high-velocity missiles striking a frangible material such as stone or concrete, it is not always the case that the angle of ricochet is less than the angle of incidence. There are, however, a few generalizations which can be applied.ġ. Empirical studies should, therefore, be carried out for each individual case. The parameters affecting the potential to ricochet are so diverse, however, that it is difficult to lay down any firm and fast rules as to ricochet potential. Several other papers (Jauhari and Mohan, 1969 McConnell, Triplett and Rowe, 1981 Hartline, Abraham and Rowe, 1982 Rathman, 1987) have also investigated the effects of shotgun pellets ricocheting from steel and concrete. Probably the most authoritative work was by Lucien Haag (1975). The hollow- point nose did, however, collapse on impact, effectively increasing the angle and allowing the bullet to ricochet from the glass.Ĭonsidering the number of times in the investigation of armed crime that incidents of ricocheting bullets are encountered, it is surprising how little literature there is on the subject. In this instance, the angle of the screen was clearly insufficient to support a ricochet with a round- nosed bullet. The second bullet fired was a round-nosed fully jacketed bullet which cleanly penetrated the glass narrowly missing the driver. This bullet was located at a later stage and was found to have a mirror-like flat surface on the lead portion of the nose. The first round fired at the front windscreen had a hollow-point bullet which cleanly ricocheted from the screen leaving a stripe of lead up the glass. The front windscreen of a British taxi is only angled back by approximately 15 ° and under normal circumstances, such a low angle would not be expected to support a bullet ricochet. The weapon involved was a 0.357" Magnum revolver which was loaded with semi-jacketed bullets, some of which had a hollow point and others which had a solid round nose. Factors such as bullet shape, construction, velocity and ricocheting surface all have a pronounced effect on the outcome (Figure 4.31).Ī case illustrating how variable this can be involved the shooting at a taxi in central London by a terrorist group. Predicting this critical angle for any bullet/surface configuration is, however, extremely difficult. The actual degree at which a bullet will ricochet from a surface is called the critical angle. This is contrary to the popular belief that a ricocheting bullet will carry further than one fired at the elevation for maximum range. After ricocheting from the surface, the missile will lose a considerable amount of its velocity (anything up to 35% in test firings) and, invariably, lose its stability. When a bullet strikes any surface, there is a critical angle at which the bullet will bounce off or ricochet from the surface rather than penetrate.
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