Let's keep it simple and organized.
Do not bring in assault weapons or hicap magazines.
Remember, a semiauto centerfire rifle w/flash hider is an AW. A semiauto centerfire pistol with a threaded barrel is an AW. Make appropriate modifications to these before you bring them into CA - M1As and Mini14s can have muzzle brakes or bare muzzles instead; guns like HK USP Tacticals can have threaded barrels replaced.
Folks moving into CA with handguns are called 'personal handgun importers' and have 60 days to register their handguns with Calif. DOJ ($19 per gun). The form is available on the Calif. DOJ Firearms Division website and can be Googled.
Even though you can't bring in hicap magazines, you can bring in guns that take them - Glocks, Sigs, HKs, Berettas, etc. are all fine.
You can indeed bring in handguns that are not on Calif's "approved list" of "safe handguns". Should you decide to, you can even sell them later (once you get CA ID) to another Californian via "private party transfer" - but you cannot sell them to a gunshop for them to sell inside CA to another person, since that's a regular sale and not a private-party transfer ("PPT").
Bill Wiese
San Jose, CA