AFTE Store - Variation of Markings on Primers of Expended Cartridge Cases: Analysis of Cartridge Cases Fired from Caliber .25 Semi-Automatic Pistols

The relative positions of the extractor and ejector markings on cartridge cases are known as class characteristics of semi-automatic pistols and these have been used by some for listing the possible source firearm. However, the expended cartridge cases fired from pistols of small caliber such as 6.35mm or .25-caliber often exhibit no visible extractor or ejector markings. They will, however, possess a firing pin impression and often bear breech face markings. To evaluate the availability of markings on primers for the estimation of type and make of firearm, the author examined the markings on 323 expended cartridge cases fired from more than forty makes of .25-caliber semi-automatic pistols. The diameter and eccentricity of the firing pin impressions and firing pin aperture markings were measured. The degree of back flow of the primer around the margin of the firing pin impressions and the pattern of breech face markings were also noted and evaluated. The author found great diversity among the markings on primers fired from the same make of firearm. It was difficult to estimate the make of firearm using the markings on primers.