Divergent gunshot residues and characterization of the memory effect in a .22 caliber revolver and pistol

Abstract Background The forms and compositions of primer gunshot residue (GSR) in shooting cases have been routinely analyzed many crime labs by scanning electron microscope/energy-dispersive X-ray spectroscopy (SEM/EDS). Gunshot studies over the last 30 years identified a contribution residual GSR from surfaces within firearm to (the “memory effect”). In this study, we first focus on compositional differences between target, bore, cylinder gap for .22 caliber revolver which has received little attention literature. Secondly, examine behavior elements involved pistol. Results GSRs were determined 11 discharge series. Breech pistol changed sequential discharges revealing individual bullet elements. target some ammunitions not spherical. Conclusions For revolver, are divergent. Analysis pistol’s breech indicated mixing with previously deposited resulting or loss redeposition new composition. Aluminum did contribute GSR. composition its internal parts represents complex process likely involves number variables including, but restricted design, composition, pressure temperature gas, surface