Gun Standard Helps Match Shells to Crimes

New National Institute of Standards and Technology standard will help police link cartridge cases recovered at crime scenes to specific firearms.

by / August 9, 2012
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Law enforcement agencies may find it easier to link recovered shell casing with crimes now that the National Institute of Standards and Technology (NIST) has developed a new archival standard that combines the efforts of the Bureau of Alcohol, Tobacco, Firearms and Explosives and the FBI, NIST announced Aug. 8. The new standard uses physical replicas of found cartridges along with digital replicas.

Both the physical and digital replicas of found cartridges contain unique data that amount to a gun fingerprint — a firing pin impression, a breech face impression, an ejector mark and striations on the bullet. The digital images are entered into a national database called the National Integrated Ballistic Information Network (NIBIN). Where the new standard shines is the presence of a physical copy of the cartridge. If a cartridge is found at a crime scene, forensic investigators will have more confidence when matching the found cartridge to an image in NIBIN because the physical replica can corroborate the match.

"The electroforming process is so accurate that the replica cartridge cases made using it have signature marks that are less than a few micrometers — millionths of a meter — different from those on the master," said NIST mechanical engineer Alan Zheng, one of the team members who developed the reference casing.