Gunshot residue
（重定向自Paraffin test）
Gunshot residue (GSR), also known as cartridge discharge residue (CDR), "gunfire residue"(GFR), or firearm discharge residue (FDR), is residue deposited on the hands and clothes of someone who discharges a firearm. It is principally composed of burnt and unburnt particles from the explosive primer, the propellant—and possibly fragments of the bullet, cartridge case, and the firearm.