AFTE Store - The Effect of High Velocity and Low Bullet Weight of Caliber .223 Remington Ammunition on Land and Groove Impression Widths

Based on previous research and reports of land and groove impression width measurements inconsistent with the class characteristics of the firearm from which they were fired, the combination of high velocity and low bullet weight in caliber .223 Remington ammunition was analyzed to determine if this combination of variables was the cause of any notable measurement inconsistencies. Two firearms were used to test fire twelve groups of ammunition, having various velocity and weight combinations. Barrel casts of each firearm were made and the impressions were measured for the true land and groove width dimensions, and these measurements were compared to the land and groove impression width measurements of the test-fired bullets for each respective firearm. No notable differences were observed between the land and groove impression width measurements of the test-fired bullets and the rifling measurements taken from the corresponding barrel casts. Examiners are still urged to proceed with caution when making an elimination on class characteristics, based solely on differences in land and groove impression width measurements. Following this research, the opportunity exists not only to repeat and expand this research in the same caliber and in other calibers, but also to further explore the potential occurrence of such a discrepancy by examining the effect that downloading may have on land and groove impression widths.