Penal Code § 32415
ARTICLE 2. Exceptions Relating Specifically to Large-Capacity Magazines
Section 32310 does not apply to the loan of a lawfully possessed large-capacity magazine between two individuals if all of the following conditions are met:
(a) The person being loaned the large-capacity magazine is not prohibited by Chapter 1 (commencing with Section 29610), Chapter 2 (commencing with Section 29800), or Chapter 3 (commencing with Section 29900) of Division 9 of this title or Section 8100 or 8103 of the Welfare and Institutions Code from possessing firearms or ammunition.
(b) The loan of the large-capacity magazine occurs at a place or location where the possession of the large-capacity magazine is not otherwise prohibited, and the person who lends the large-capacity magazine remains in the accessible vicinity of the person to whom the large-capacity magazine is loaned.