Distribution of lead and barium in gunshot residue particles derived from 0.22 caliber rimfire ammunition.

0.22 caliber rimfire ammunition is commonly encountered in firearms incidents in Australia. This paper reports on work which has confirmed the nonhomogeneous nature of gunshot residue (GSR) particles and that the lead and barium distribution within particles varies significantly with the particle size and structure. The outcome has been an improved understanding of how the particle formation influences the ability to determine the origin of GSR derived specifically from 0.22 caliber rim fire ammunition.