Table 2 Listing of the GSR examinations from the S&W revolver. A Series number and type, BW, bore wipe sample; T, target sample; CG, cylinder gap sample. B The primer composition, bullet surface composition, and number of shots with that primer and bullet prior to the sample taken after the last shot. C Previous shots of that series in B have a different primer and bullet composition than the final shot. D The number of GSR particles that were EDS sampled for the final shot of the series

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