California's assault weapons ban, when it went into affect in 1989, required that people who already owned guns that met the definition of assault weapon to register them. Once registered that gun cannot be sold, transferred in any way within the state, or even passed down to next of kin. Upon death the estate's only options are surrender to the state or remove it from the state immediately.
They have at least twice expanded the definition of guns that meet that definition. Each time guns already in circulation had to be registered and thus become subject to what I stated above.
The intent is undeniable. Is it busting down our doors and searching our homes? No, it's far more effective than that.