The shooter washed and dried his hands prior to firing, and the weapon was also cleaned prior to firing. The same weapon was used for all firings, a Smith and Wesson Model 10-8 revolver with a 2-inch barrel. After firing, the shooter left the firing room and his hand was sampled by the researcher. The efficiency of particle collection was examined based on the number of rounds fired, temperature, and shelf life. The tape lift surface demonstrated excellent particle collection ability, and it remained stable for all conditions tested. Glue lift was less efficient under all conditions tested. Collection followed by concentration gave highly variable results. It was found that GSR may be lost in the concentration method in at least three possible areas: particles lost from the nonadhesive Nucleopore filter when it was teased away from the subfilter; actual particles not counted due to contamination of the subfilter; and particles trapped in debris and either aspirated out of the concentrator or pelleted onto the filter surface. 17 references, 6 tables, and 7 figures (Author abstract modified)