Cal. Penal Code § 16630

As used in this part, “gunsmith” means any person who is licensed as a dealer pursuant to Chapter 44 (commencing with Section 921) of Title 18 of the United States Code and the regulations issued pursuant thereto, who is engaged primarily in the business of repairing firearms, or making or fitting special barrels, stocks, or trigger mechanisms to firearms, or the agent or employee of that person.