That's not a state-wide law (wherever this is)?
It stuck out with me because it seems a little outside the scope of a "local ordinance"... which I equate with not spitting on the sidewalk or somesuch.
To the best of my knowledge it's just local. I don't recall anything on that in the state statutes but I may be wrong.
As an aside to all of this, does it seem strange to anyone else that Kelly would be keeping the pistol which is the same basic type of weapon used against his wife, while giving up the AR? By the way, there is a piece of legislation pending that clarifies the state statute regarding what cops have to do with confiscated or found firearms (sell them to an FFL) to make sure that it also covers abandoned firearms...such as in buyback programs.