Gun Shot Residue
Gun Shot Residue (GSR) are sooty deposits of lead and various other elements from the primer mixture, or may be an actual powder residue or chunks of unconsumed powder particles that are left on a surface. GSR occurs as a result of the firing pin of a firearm striking the primer cap on ammunition
Stippling
Stippling are impact sites located on a surface that are produced by the unconsumed powder particles in GSR striking that surface.
Documentation of GSR and Stippling
When GSR or stippling is observed, it should be first documented with overall, mid-range and close-up photography. A photo marker should then be added to the area, and additional overall, mid-range and close-up photographs should be taken with a scale in place.
The closer a firearm is to a surface when it is fired, the more concentrated the GSR and stippling will be. The type of firearm and type of ammunition impact the appearance of GSR and stippling as well.