Forensic firearm identification of semiautomatic handguns using laser formed microstamping elements

Abstract

For well over one hundred years the science of Firearm and Tool Mark Identification has relied on the theory that unintentional random tooling marks generated during the manufacture of a firearm onto its interior surfaces are unique to each individual firearm.^[1][2] Forensic Firearm and Tool Mark Examiners have had to rely on the analysis of these randomly formed unintentional striations, or scratches and dings, transferred onto ammunition components from firearms used to commit crimes, as a way of developing clues and evidence. Such transfers take place during the cycle of fire and ejection of the cartridge from the firearm during the commission of a crime. The typical striations on the cartridge casings are caused by tooling marks that are randomly formed during the machining of interior surfaces of the manufactured firearm and by other firearm components that come in contact with the cycling ammunition. Components like the firing pin, extractor and ejector, impact the surfaces of the cartridges as they are fed, fired and ejected from the firearm. When found at a crime scene, these striae constitute ballistic evidence when effectively analyzed by a Forensic Firearm and Tool Mark Examiner. Examiners categorize these striations looking for matches to be made between the components that created the marks and the recovered firearm. Reality is that nearly 50% of firearms used in violent crimes are not recovered at a crime scene, requiring the analysis to be processed and logged into evidence files or imaged into reference image databases for future comparison whenever a firearm might be recovered. This paper will present a unique law enforcement technology, embedded into firearms for tracking the sources of illegally trafficked firearms, called Microstamping. Microstamping is a laser based micromachining process that forms microscopic "intentional structures and marks" on components within a firearm. Thus when the firearm is fired, these microstamp structures transfer an identifying tracking code onto the expended cartridge ejected from the firearm. Microstamped structures are laser micromachined alpha numeric and encoded geometric tracking numbers, linked to the serial number of the firearm. Ballistic testing data will be presented covering microstamp transfer quality, transfer rates and survivability/durability. Further information will provide an overview on how microstamping information can be utilized by law enforcement to combat illegal firearm trafficking.