You are getting this a little bit backwards. The CA law does not require bullet buttons. The law requires that you need to use a tool to remove the magazine. The bullet button is a workaround that gun dealers devised in order to continue selling firearms with removable magazines. The legislators were trying to ban removable magazines.
What I’m saying is this roadblock is futile because misuse can easily be attained by slight modification.
Just leave the guns as stock elsewhere.