I live in Northern CA.
Be very careful in your selection of .223 semi-auto rifles. I would suggest contacting a range that has CMP matches to see what types of rifles seem to do well. California has one of the more "intense" anti-Assault Weapons law sets of definitions.
I use to live in California, but moved out long ago. I once called up the State Dept of Justice to ask about an M1-Paratrooper Carbine I inherited from my father-in-law. Even though the 30 Cabine is so weak, you can't leagally use it to hunt big game, the M1-Carbine with folding stock, bayonet lug, pistol grip, and ability to take a "large" capacity magazine is considered so evil to own, I would have to have it welded or cut prior to taking it into the state if I ever moved back. Or as the lady at the State's Dept. of Justice told me, I could surrender it to a law enforcement agency and have them destroy it.
Be very careful. Some manufacturers have "California models" of various "military style" semi-auto rifles. Some of them have skirted the rules by not providing bayonet lugs, no flash supressors, no pistol grips, no detachable magazines that are also "small," etc.