AFTE Store - Striae Reproducibility On Sectional Cuts of One Thompson Contender Barrel

The purpose of this study was to determine the persistence of reproducible striae on bullets after remove of one-inch barrel sections. The comparison of striae on bullets from adjacent sections of such a barrel is analogous to the comparison of striae from consecutively produced barrels. Wire electron discharge machining was the method of choice for cutting the barrel sections leaving no visible burs under high magnification. A total of six one-inch sections were removed. Bullets test fired from a section were first compared to each other and then to bullets test fired from adjacent sections. These comparisons utilized an objective methodology for comparison, which consisted of tabulating the number of lines, number of matching lines, and number of consecutive matching lines for each land and groove impression. Percent match, average striae count, and the probability of finding at least one event (single, double, triple, etc.) in a land or groove impression were subsequently calculated. The results of the study show that striae on bullets were significantly altered by the removal of the one-inch barrel sections.