Utah passes exemption from Federal firearm laws
Story here. The bills of this type that I have seen provide that a gun made within the State and transferred to a State resident are exempt from Federal control.
The big difficulty, as I see it, is the Raich decision on medicinal marihuana, holding that growing and using marihuana in-State (and I think persons were forbidden to sell it) came within the Congressional power over interstate commerce. Absent a way around that, State enactments would be trumped by the Supremacy Clause. I haven't had time to carefully read Raich, so I don't know if there is a way around it. On the other hand, there may be considerations here which extend beyond legal doctrine -- the fact that the people of certain States are beginning to act on their beliefs regarding a proper view of federalism.
Hat tip to reader Bret Gallo....