California allows FFL sales of illegal or restricted weapons to out of state buyers. That is how they get around the just compensation rules and precedence. When the Asault weapon registration and ban came in during the early 90's, I registered my 2 AR 15's just so I could use them without looking over my shoulder. They had to be declared, purchased and registered before a cut off date or they could never be legal in the state without things like magazine buttons and that sort of thing. The over 10 round magazine ban was grandfathered in. Many magazines have a build date stamped into them so any made before the ban were legal to own as long as they couldn't prove they were purchased after the cut off date.