A preliminary evaluation of the use of gun bluing to enhance friction ridge detail on cartridge casings

Friction ridge detail was enhanced on fired and unfired 9mm brass luger ammunition casings using three techniques, two involving Gun Blue reagent at a concentration of 50% v/v. Fingermarks were deposited on a total number of 90 ammunition casings and half were discharged using a Glock 19 semiautomatic pistol. Mark development was achieved using either Superglue Fuming followed by Basic Yellow 40 Fluorescent Dye Staining (SG-BY40), Superglue Fuming followed by Gun Blue (SG-GB), or Gun Blue (GB) as a single process. All three processes developed ridge detail on both fired and unfired casings. The results of this preliminary work show that the use of Gun Blue as a single enhancement technique was able to enhance ridge detail of the highest quality and clarity particularly on fired casings, making it the most effective process.