Which characteristic defines individual markings found on firearms?

Individual markings on firearms are defined by unique marks that can identify a specific gun. Each firearm, particularly the barrel, ejector, and extractor, exhibits distinctive characteristics that arise from the manufacturing process and the wear and tear over time. These individual markings are created through various factors, including imperfections in the manufacturing, the use of specific tools, and even differences in how the gun is used or maintained.

Forensic ballistics relies on these unique markings to match bullets and cartridge cases recovered from crime scenes to a specific firearm. When law enforcement or forensic experts examine fired bullets or cartridge cases, they look for these unique features, such as rifling patterns and striations, that can conclusively link a piece of evidence to a specific gun. This principle is essential in the field of forensic science, allowing investigators to establish a connection between a firearm and a crime.