How does studying the rifling pattern of a gun help in CSI?

How does studying the rifling pattern of a gun help in CSI?

Richard Saferstein (Former Chief Forensic Scientist) gives expert video advice on: How does the study of firearms help in CSI?; How does a gun work?; How are firearms and ammunition collected in CSI? and more...

When a manufacturer of a weapon creates rifling, or lands and grooves within the inner morals of a barrel, there are a variety of techniques that are used and the variety of lands and grooves that can be used. So what is looked for are, a) the number of lands and grooves, b) the direction of twist and c) the angle of twist. Knowing these perimeters will help a forensic investigator perhaps identify the make and model of a weapon that was used in a crime.