Cal. Penal Code § 1542.5

Notwithstanding any other law, with regards to a search warrant issued upon the grounds specified in paragraph (14) of subdivision (a) of Section 1524, the following shall apply: (a) The law enforcement officer executing the warrant shall take custody of any firearm or ammunition that is in the restrained person’s custody or control or possession or that is owned by the restrained person, which is discovered pursuant to a consensual or other lawful search. (b) (1) If the location to be searched during the execution of the warrant is jointly occupied by the restrained person and one or more other persons and a law enforcement officer executing the warrant finds a firearm or ammunition in the restrained person’s custody or control or possession, but that is owned by a person other than the restrained person, the firearm or ammunition shall not be seized if both of the following conditions are satisfied: (A) The firearm or ammunition is removed from the restrained person’s custody or control or possession and stored in a manner that the restrained person does not have access to or control of the firearm or ammunition. (B) There is no evidence of unlawful possession of the firearm or ammunition by the owner of the firearm or ammunition. (2) If the location to be searched during the execution of the warrant is jointly occupied by the restrained person and one or more other persons and a locked gun safe is located that is owned by a person other than the restrained person, the contents of the gun safe shall not be searched except in the owner’s presence, and with his or her consent or with a valid search warrant for the gun safe. (c) This section shall become operative on January 1, 2016.