Gunshot entrance wound abrasion ring width as a function of projectile diameter and velocity

The relationships between gunshot entrance wound abrasion ring widths versus projectile diameter and velocity, using foam-backed deer hides as targets, were investigated. At a fixed velocity, abrasion ring width increased with increasing projectile diameter but decreased in proportion to the central defect diameter. For fixed-diameter projectiles, very slow and high velocities produced minimal abrasion width. Maximal abrasion width occurred at intermediate velocities. The authors postulate that abrasion width is a function of the ratio of projectile velocity and the maximum deformation velocity of the target skin. The largest abrasion width occurs when the ratio is one. Using a projectile velocity known to produce maximum abrasion width at an initial warm temperature, then decreasing the target deformation velocity by cooling, produced the expected results of decreasing abrasion width.