As long as its in a locked case unloaded you will have no problems. Ideally in the trunk, unloaded and in a locked case. The magazines are illegal to import in to the state if they hold more then 10 rounds. The grandfather clause only works if you had them IN California prior to 2000, and which would be impossible as this firearm only recently was made.
Good luck on the trip!
12020. (a) Any person in this state who does any of the following is punishable by imprisonment in a county jail not exceeding one
year or in the state prison:
(2) Commencing January 1, 2000, manufactures or causes to be manufactured, imports into the state, keeps for sale, or offers or exposes
for sale, or who gives, or lends, any large capacity magazine.