Cal. Penal Code § 30330

Nothing in this article shall apply to or affect the sale to, purchase by, possession of, or use of any ammunition by any member of the Army, Navy, Air Force, or Marine Corps of the United States, or the National Guard, while on duty and acting within the scope and course of employment, or any police agency or forensic laboratory or any person who is the holder of a valid permit issued pursuant to Article 3 (commencing with Section 18900) of Chapter 1 of Division 5 of Title 2.