Working Mechanisnti of Firearm And Its Parts - A Foremsic Perspective

Law enforcement agencies have relied upon the science of "forensic ballistics" to link fired bullets and cartridge cases to each other and to alleged firearms. At a crime scene, physical evidence is routinely encountered, for example, fired shells, bullets, gunpowder residues on the body or clothing of victims or perpetrators. These ar(> knowingly or unknowingly left by the culprits at the scene of occurrence. The underlying principle is that when a tool (firearm) acts on some object (cartridge) it will leave marks, which is unique due to the configuration of the firearm. The uniqueness of each weapon is a result of manufacturing processes and post manufacturing wear and damage. Every gun leaves its own unique microscopic markings on the surface areas of fired bullets and cartridge cases. Experts compare these markings in an effort to identify similarities that positively link them together, subsequently concluding that the ammunition components were fired from the same firearm. Experts who undertake examinations and studies in this field are referred as 'Ballistics Experts' or 'Firearm Examiner'. A ballistics expert employs basic scientific principles to propose a hypothesis of a shooting incident follov/ed by testing it through series of experiments, collects & compiles various data to form a logical conclusion and/or to offer expert opinion. In shooting incidents, it is often required to establish that whether it v^'as a case of suicide, homicide or accidental. This paper gives a basic knowledge about the understanding of working mechanism of firearms & ammunition and their method of identification, which may largely be benefited to invesligating officers (lOs), law enforcement agencies, students and other scientific community.