Cal. Penal Code § 32455

Section 32310 does not apply to the sale, gift, or loan of a large-capacity magazine to a person enrolled in the course of basic training prescribed by the Commission on Peace Officer Standards and Training, or any other course certified by the commission, nor to the possession of, or purchase by, the person, for purposes of participation in the course during his or her period of enrollment. Upon completion of the course the large-capacity magazine shall be removed from the state, sold to a licensed firearms dealer, or surrendered to a law enforcement agency, unless another exemption to Section 32310 applies.