Bullet calibre and types estimation from gunshot wounds in sus scrofa (linnaeus) long bone

Abstract

The calibre of bullet used in the commission of crime is not typically ascertained from a wound in soft tissue, and cannot be reliably determined from the damage done to flat bones (1, 2). This study examined the feasibility of obtaining both bullet calibre and type from ballistic damage to long bones. Thirty fresh pork shoulders (Sus scrofa), in three groups of ten, were each shot with a handgun using one of three calibre. These calibres were of two bullet types, either lead or full copper jacket. Each pork shoulder was shot through the intact humerus with either a 0.22 round-nose lead bullet, 9mm full copper jacketed bullet, or a 0.38 round-nose lead bullet. The long bones were subsequently defleshed and examined for evidence of bullet calibre and type. The damaged bone was reconstructed to the fullest extent possible from the resulting bone fragments. The minimum diameter of each entrance wound, as well as the associated fracture pattern, were recorded. A Kruskal-Wallis nonparametric test was used to compare the median entrance wound measurements for each calibre. Cortical bone spalling was seen only In long bones shot with a copper jacketed bullet. This is due to the differing energy propagation of the two bullet types through the bone tissue. Our study demonstrates that bullet type can be ascertained from long bone damage, and the damage from a 0.22 calibre bullet can be distinguished from that of a 0.38 or a 9mm bullet.