Study Compares Gun Barrels and Bullets

This study provides a solid validation of the foundations of ballistic identification by assessing the individuality and repeatability of features and transfer between a barrel and a bullet. Although a number of parameters influenced the individuality and repeatability of the results, the manufacturers of the firearm barrel and the bullets were key. For certain brands, the transfer of characteristics was very repeatable and the bullets could be identified with accuracy. However, for a group of low-end, relatively inexpensive firearms, repeatability could not be discerned. The study developed and used a 3D-based ballistic analysis system to determine quantitative criteria that should be used to establish a gun’s individuality; the quantitative criteria that should be used to establish that a specific gun fired a specific bullet; and whether it is possible to estimate the probability of a bullet/gun match being incorrect. A description of the Daubert Standard and its impact on forensic evidence was included. Data were collected over a three-year period and involved firing 2,800 bullets using 9 different brands of weapon barrels and 2 different types of ammunition. The Baltimore County (MD) Police, Washington State Police, and the FBI collaborated on this project.