Law enforcement agencies submit firearms, bullets or cartridge cases to the Minnesota Bureau of Criminal Apprehension Forensic Science Services.  Firearm examiners compare bullets and cartridge cases to determine if they were fired in the same firearm or in a particular firearm.  Firearm examiners use a comparison microscope to simultaneously view and compare two cartridge cases or bullets.

 

The microscope magnifies the specimens allowing examiners to see very small marks left on their surfaces during the firing process.  Examiners look for corresponding features on the bullets and cartridge cases to determine if they “match”.