AFTE Store - On the Matter of Chronograph Calibration

A method is proposed for the calibration and periodic performance testing of ballistic chronographs. Organizations such as ASCLD/LAB and ISO 17025 may require such calibration for instruments that will be used during forensic testing. The use of a reference rifle-ammunition combination of known performance or a procedure involving an inter-comparison of two contemporary chronographs positioned in a parallel configuration is proposed to establish satisfactory performance of the unit destined for casework. Although not commonly available to crime laboratories, certain Doppler radar units offer a third means of testing and comparing performance on actual projectiles measured by both systems at the same time and distance from the muzzle of the reference firearm. Once a chronograph’s performance level is established and found to be acceptable, it is recommended that an internal source of ammunition and a specific firearm be dedicated exclusively for the purpose of regular, periodic performance testing and validation for that chronograph.