What is a Firearm’s Examiner, and what do the bullets represent? By: Janine Stizzo - Firearms Familiarization class- 2/7/2015
The Firearm and (Toolmark) Examiner has the job of examining evidence when there is no actual weapon found at a crime scene, and only the remnants of bullets shells and casing left behind. Additionally, firearms evidence submitted to the examiner’s lab, will typically include the firearm found (if any), fired bullets, spent cartridge cases, spent shot gun shells, and, even live ammunition sometimes.
Firearm Examiners perform various tests, based on the information and evidence that is submitted to the lab at the time of the crime and/or incident. Let us take a look at the various types of markings and tests that are administered by the Firearm Examiner and how they developed, dating as far back as to the 15th century.
Beginning with Rifling, which first made its first appearance in the 15th century, is the process of making grooves into gun barrels that “imparts a spin to the projectile for increased accuracy and range”. General rifling characteristics (GRC), are identified rifling patterns and the diameters of the individual lands and grooves. Using these specific parameters, firearm examiners can search through a large database of already known rifling data. The results of their specific search will assist the firearms investigator to narrow down the search for the unknown firearm, and speed up the entire process overall. Bullets fired from rifled weapons acquire a distinct signature of grooves, scratches, and indentations which are of value for matching a fired projectile to a firearm. Furthermore, Firearms Identification is actually a form of Tool mark Identification as well, where the firearm is made of a material harder than the ammunition components, which in turn, acts as a tool to leave impressed or striated marks on the various ammunition components that come into contact with the firearm.
Like bullets, Cartridge...