SBI to Begin Using New Reference Standard to Assist Examiners in Identifying Cartridge Casings

A new reference standard for comparing cartridge casings has been developed by the National Institute of Standards and Technology (NIST). The standard is known as SRM 2461, Standard Casing. It was developed to assist firearms examiners by ensuring that the equipment used to match cartridge cases to those in the National Integrated Ballistic Information Network (NIBIN) database is calibrated correctly. Joseph R. John, Sr. Director of the North Carolina State Crime Lab, has confirmed that firearms examiners are to begin using this standard.

Examiners use a microscope called an Integrated Ballistic Identification System (IBIS) to view breech face marks, ejector marks, and firing pin impressions on a casing, which serve as identifying characteristics for a specific firearm once recorded in the NIBIN database. SRM 2461, Standard Casing consists of two standards, a master cartridge case with distinct markings and a digital image contained in the NIBIN database that has the same marks. If the examiner can match the standard to the digital image in the NIBIN database, the technician can have confidence that their equipment is calibrated properly. NIST claims that the new standard will allow examiners to have confidence in their methodologies and demonstrate that their work uses a national standard.

The use of the new standard casing may create some interesting opportunities for defense attorneys working with cartridge casing evidence.  For attorneys working on older cases, it raises questions regarding the absence of a national standard in the past to ensure against inaccuracies. Attorneys working on cases where SRM 2461, Standard Casing is used should keep in mind that the standard only addresses calibration. Questions about the reliability and error rate of the technique are not addressed by this calibration standard.

More information about the new standard is available here.