California Code, Penal Code - PEN § 27531

(a) “Microstamp” means a microscopic array of characters that may be used to identify the specific serial number of a firearm from spent cartridge casings discharged by that firearm.

(b) “Microstamping component” means a firing pin or other component part of a semiautomatic pistol that, when installed, produces a microstamp on at least one location of the expended cartridge case each time the pistol is fired.

(c) “Microstamping-enabled” means either of the following:

(d) “Producing microstamping components” may include, but is not limited to, the process of engraving a firing pin to modify the pin into a microstamping component.

(e) “Semiautomatic pistol” means a pistol, as defined in Section 16530, that has an operating mode that uses the energy of the explosive in a fixed cartridge to extract a fired cartridge and chamber a fresh cartridge with each single pull or activation of the trigger.