I can't speak to the ultimate legality of your idea, but I would guess that one would be arrested and it would be up to your lawyer to demonstrate that you were

I can't speak to the ultimate legality of your idea, but I would guess that one would be arrested and it would be up to your lawyer to demonstrate that you were acting within the bounds of the law (if you were). To your first question, I think it's fair to say that both NJ and NYC (and because of NYC, NY to a lesser extent) are generally perceived as being hostile towards firearms and general weapons ownership. If I were to predict states that restricted possession of an inoperable or antique firearm, NJ and NY would be at the top of my list, in that order. To your second question, the appearance of the object has no bearing on it's legal status as a firearm (laws prohibiting look-alike objects notwithstanding). A pistol frame or lower receiver, incapable of being anything but a paperweight without all the other parts, is a firearm for legal purposes and would get one busted in the same manner as if it were a completely operational firearm. Weapons laws are nuanced, pedantic, and frustrating. Frequently, they make no rational sense.