Quantitative assessment of barrel wear from solid copper bullets

Abstract

Forensic firearm analysis is based on the principle that firearms impart individual characteristics on bullets and cartridge cases during the firing process, and these individual characteristics can be used to trace a bullet or cartridge case back to the firearm that shot it. For bullets, these characteristics are created by the features inside the barrel. However, these features are subject to change and wear, and this can lead to the inability to identify the firearm that shot a specific bullet. There are many ammunition types on the market, and each type may affect barrel features differently. Literature in the field primarily focuses on the effect of conventional ammunition (i.e., jacketed lead core). One study has been conducted on solid copper bullets, and it indicates that they may have a greater effect on barrel individual characteristics than conventional ammunition. The goal of this research was to determine how solid copper bullets affect barrel rifling characteristics after the successive firing of 500 rounds through a new Glock 19 Gen 5 with a Glock Marksman Barrel. From the 500 bullets, 68 were collected for further analysis. The first ten and last ten bullets were used to profile the barrel characteristics at the beginning and end of the study while every tenth bullet was collected to track any changes in the features. Three-dimensional scans of the land engraved areas (LEAs) were generated using the Cadre Forensics Versa system. Cadre Forensics' implementation of the Congruent Matching Profile Segments algorithm was used to compare the depths of the LEAs. The data were analyzed using the Kwiatkowski-Phillips-Schmidt-Shin time series test, and it showed that the data exhibit a significant decreasing trend. Based on the algorithm scores and visual examinations of the LEA scans and depth profiles, this study demonstrates that solid copper bullets have a significant effect on the individual characteristics within firearm barrels.