California Code, Penal Code - PEN § 30420

(a) A member of the Armed Forces of the United States or the National Guard, while on duty and acting within the scope and course of employment, or any law enforcement agency or forensic laboratory.

(b) A common carrier licensed under state law, or a motor carrier, air carrier or carrier affiliated with an air carrier through common controlling interest that is subject to Title 49 of the United States Code, or an authorized agent of any such carrier, when acting in the course and scope of duties incident to the receipt, processing, transportation, or delivery of property.

(c) An authorized representative of a city, county, city and county, or state or federal government that receives an unserialized firearm precursor part as part of an authorized, voluntary program in which the governmental entity is buying or receiving firearms or firearm precursor parts from private individuals.