_Diagnosis._--The only diagnostic point which it is necessary to consider in this chapter is the determination of the nature of the bullet which has caused the particular injury under observation, and this is more a matter of interest than importance. The primary indication lies in the size of the aperture of entry, which naturally varies with the calibre of the bullet employed, and the difference, except in the case of large projectiles, is not always easily determined, unless we can be sure that the impact of the bullet was at right angles. In the latter case it is possible to distinguish even between, for instance, a Lee-Metford and a Mauser wound, if the resistance likely to be offered by the part struck is kept in mind. A ricochet bullet, on the other hand, may upset all our calculations, if size alone be taken as an indication; but here the irregularity of the wound often serves to exclude one of the larger varieties as the cause. The appearances of the exit wound are less useful in determining the nature of the bullet employed, as irregularities of outline are so much more common whatever projectile may have emerged; but examination of this wound often gives us useful information as to the existence of an injury to the bones not involving loss of continuity. [Illustration: FIG. 46.--Two flattened Leaden Cores to illustrate means of determination of nature of bullet. Note ring at base. The right-hand bullet is probably a 'man-stopping' revolver bullet; it flattened against bone] Other information beyond that furnished by the external wounds may be gleaned from the presence of fragments of lead in the wound; these, if unaccompanied by portions of casing, afford some presumptive evidence of the use of an unsheathen bullet, especially if found on the fractured surface of the bones; but it must be borne in mind that in the case of ricochet bullets the leaden core often perforates when entirely freed from its mantle. Pieces of the mantle again may give useful information both from examination of their thickness and composition. Lastly a naked core nearly always retains the marking on its base corresponding to the turning over of the mantle, this not being likely to suffer impact calculated to efface the groove. When this groove existed the employment of any of the soft-nosed bullets used in this campaign might be safely excluded (fig. 46).