Hi Josh, welcome to Calguns and thank you for serving.
Could you please provide us with some more information on your firearms that aren't CA legal. If by chance you mean handguns that are not on the CA approved list then you may have a misconception of the list. Handguns not on the list are legal to own as long as they do not violate CA AW laws, threaded barrel, etc. The list only covers what a CA FFL can sell to the general public, LEO's are exempt from the list.
If you have an AR or AK not banned by name then they too are legal if you add a bullet button or make them featureless and only use magazines that hold 10 or less rounds.
You can bring magazines but any that hold more than 10 rounds must be disassembled before entering CA and not reassembled while in CA.
Don't try to make sense of our laws, they were enacted based on emotion, not logic.