AFTE Store - The Effect of Subclass Characteristics Involving Shotgun Ammunition on IBIS Entries and Correlation Results

Four experiments were conducted in order to determine the affect that subclass characteristics have on the correlation scores produced by the Integrated Ballistics Identification System (IBIS). Specifically, parallel manufacturing marks, which are present on the primers of certain lots and brands of 12 gauge shotgun ammunition, were examined. Since IBIS only ‘sees’ shades of gray and cannot tell that markings are or are not individual in nature, the responsibility falls on the examiner to thoroughly check all ammunition prior to use in casework. Before any experimentation, several brands of ammunition were examined for the presence of manufacturing marks. Then, in each of the four experiments, variables were tested in order to determine the affect that these marks have on the IBIS correlation process. Failure of the technician to recognize these markings on the ammunition prior to test firing a weapon and acquiring images can cause IBIS to erroneously treat subclass characteristics as individual ones.