AFTE Store - Computerized Image Analysis for Firearms Identification; The Integragted Ballistic Identification System (IBIS) BRASSCATCHER Performance Study

The Bureauof Alcohol, Tobacco and Firearms (ATF) San Francisco Laboratory Center has conducted a Performance Study of the IBIS BRASSCATCHER hardware and software used in acquiring and correlating breech face and firing pin impressions on expended cartridge casings. Pairs of casings from over 200 pistols representing .25, .380, 9mm, .45 calibers were correlated. There was no microscopic pre-screening of the cartridge casings prior to selection for testing. The correct “twin” casing was found in the first position of ranked scores between 58 to 78 percent of the time, and 74 to 93 percent of the time in the top five positions. The correct “twin” casing was found in the first position 94 percent of the time for a Glock 9mm caliber pistol database. Visual subjective estimations of cartridge casing “matchability” show that images judged “good” and “fair” in quality constituted the bulk of “first position ” matches selected by the computer. However, a sizeable number of “poor” quality images of matching casings were still found in the top scoring position.