My SO has a rifle, semiautomatic and revolver (none "assault" type weapons) packed away, from her past marriage, no reciepts (they
were legitimately obtained), bought (not in CA) over a period of 10+ years when she and her ex were indy network engineer moving from state to state working on contracts.
She maintained a residence in CA during that time and lives here now. She's concerned that she's in illegal possession of the guns under CA gun laws (they've never been registered in CA) and wants to know if and how she can "get legal". I told her I knew who to ask.