Individual Characteristics

The examination and identification of fired and unfired cartridge cases/shotshell cases are based on the following principles:

The various parts of the operating mechanism of firearms (firing pin, breech face, chamber, extractor, ejector, and other areas) can bear unique microscopic characteristics as a result of manufacturing processes, use, and abuse.
These characteristics may mark the surfaces of fired and unfired cartridge cases/shotshell cases with striated marks or impressions as they are fired in or cycled through the firearm.
These individual characteristics may be reproducible and may be uniquely identifiable with a particular firearm.

These principles and the use of comparison microscopy combine to form the conceptual and physical foundation for firearm identification.

Click images below for larger image.

Images courtesy of RCMP