Microstamping

Microstamping is a ballistics identification technology. Microscopic markings are engraved onto the tip of the firing pin and onto the breech face of a firearm with a laser. When the gun is fired, these etchings are transferred to the primer by the firing pin and to the cartridge case head by the breech face, using the pressure created when a round is fired. After being fired, if the cases are recovered by police, the microscopic markings imprinted on the cartridges can then be examined by forensic ballistics experts to help trace the firearm to the last registered owner. A California law requiring the use of microstamping technology in all new semiautomatic firearms sold in the state has attracted controversy.