The distribution of shotgun pellets on a target varies depending on several parameters, including the shotgun choke and firing distance. The resulting distribution can be characterized by the radius of a “best-fit circle” that describes the spread of the pellets. This theory was applied to hand-loaded ammunition (with variations in both powder load and bullet weight) discharged from 9mm handguns in an attempt to evaluate the manner in which these variables impact the distribution of unburned and partially burned gunshot residue (GSR).
Ref. This research was conducted in partial fulfillment of the Master of Science in Forensic Science at John Jay College of Criminal Justice (New York, New York), in collaboration with Jack Hietpas, Peter Diaczuk and Dr. Peter De Forest. Work was carried out at the Pedico Research Institute (PRI) in Pennsylvania.
Forensic Pattern Recognition & Microscopy 