Differing sizes of bullet entrance holes in skin of the anterior and posterior trunk

Abstract

The aim of the present study was to establish whether the size (diameter and area) of bullet entrance holes in skin varies between distant shots to the anterior and posterior trunk, respectively, when using the same ammunition (in concreto pistol cartridges 9 mm Luger). For that purpose, specimens of porcine skin from the belly region and the back were taken (10 samples each) and shot at from a distance of 1.6 m. The entrance holes were photo-documented under standardised conditions. After image processing for contrast enhancement, the maximum diameter and the area of each skin defect were measured automatically by means of an image analysis system. Both size parameters differed significantly depending on the body region affected. On the back with its comparatively thick dermis, the skin defects were considerably smaller than those on the ventral trunk where the corium is less thick. This difference can be explained by the fact that the elastic properties of skin are strongly determined by the connective tissue which is especially rich in fibres. The study results were consistent with the authors' casework experience and support the assumption that the entrance site of gunshot wounds has a major influence on the size of the bullet hole in skin.

Keywords: Abdominal skin; Bullet entrance hole; Dorsal skin; Size of gunshot entrance; Skin defect.

Fig. 1

Gunshot entrance wounds from distant shots using pistol cartridges with round-nosed bullets cal. 9 mm Luger. The skin hole is comparatively large on the frontal trunk (a) and considerably smaller on the back (b)

Fig. 2

The experimental design comprised 10 distant shots to porcine skin from both the back and belly region

Fig. 3

Typical examples for experimental gunshot entrance wounds in porcine skin. The dark blue colour of the epidermis is due to prior dyeing with haemalum. There is a distinct difference in size between the gunshot holes in the abdominal (a) and dorsal (b) skin. The central defects are surrounded by epidermis-free abrasion-rings appearing pale-grey. After being processed by an image editing program, the actual skin holes assumed a homogenous red colour, so that the areas could be determined by applying an analysing system

Fig. 4

Box plots of the data from the bullet entrance holes

Fig. 5

Histological sections (H&E) of porcine skin  specimens from the belly region (a) and the back (b). Note that the dermis in back skin is much thicker than in the belly region

Fig. 6

Test shots to targets having different elastic properties. On the left, the permanent entrance hole in Plasticine™ is larger than the bullet’s cross-section, whereas the size in highly elastic rubber (on the right) is much smaller than the calibre of the round-nosed projectile used (cal. .25 ACP, central picture)