Gunshot residues

There are several forms of physical evidence of relevance to investigation of offences involving firearms. The subject of this chapter neither relates to the markings that arise on ammunition components as a result of firearm discharge nor to the examination of wounds produced by shootings nor to the examination of scenes to reconstruct an offence. Instead, this chapter deals with the examination of gunshot residues (GSR)–physical evidence that is often invisible to the naked eye and is elucidated through chemical analysis. The main parts of a round of ammunition relevant to GSR analysis are the primer, the propellant, the projectile (also known as the bullet) and the cartridge case.