Precision laser etching techniques allow the firing pin and other internal parts of a firearm to be marked with unique identifiers, such as numbers and symbols invisible to the naked eye. When a round is fired, these 'ballistic fingerprints' are stamped onto the rear surfaces of the cartridge casing, then expelled from the gun and perhaps found at the scene of a crime.

Microstamping can enable forensic investigators to identify the make, model, serial number and most recently recorded owner of a firearm by comparing markings found on a discharged casing to records held in a law enforcement database.

In 2013, microstamping was first enacted into law in California for all new semi-automatic pistols sold and registered in that state.