Gunshot residue (GSR) is one of the results of firing a gun. When a bullet leaves the barrel of a firearm, it is accompanied by gases that include both burned and unburned particles of gunpowder. It also includes traces of metal from the firearm, the ammunition and the primer including the signature components of gunshot residue: lead, barium and antimony. GSR is usually found on the skin and clothing of the person who fired the gun. It may also be found in the entrance wound of the victim. This depends on how close the victim was to the gun when it was fired.