[svandamme]

Suspect only the case if you want to send it over , not if you go over there and collect it yourself.
CA doesn't require papers or background check amongst relatives. in state.

So if you go there
do paperless transfer

and then bring it back home you wouldn't need an FFL as per federal law 18 USC § 926A, every U.S. citizen may legally transport firearms across state lines if you are legally allowed to have it in both states.

But somebody local might have better intel on that (I just know cause i used to be in guns in Europe and had eye on various countries laws as I also launched an action against EU proposing new stricter legislation)