IIRC, this is part of the current AWB in CA. Visits are not mandated, but CA DOJ can come to your house without warning, warrant or cause, enter and inspect the registered weapon and related "papers" They have the latitude to make a decision whether you "need" to have the weapon anymore.
I don't know of any seizures resulting from the provision, other than the SKS confiscations in 1997.
Loyalty to petrified opinions never yet broke a chain or freed a human soul in this world — and never will.
— Mark Twain