I still think that the best and most straightforward interpretation of the second amendment is that the Federal government established and limited by the US Constitution has absolutely no authority whatsoever to limit anyone's right to keep and bear arms for any reason, but that state and local governments still have the power to regulate the use of arms as they deem appropriate within their jurisdictions.
There were plenty of local firearms regulations at the time that the 2nd amendment was ratified (and centuries earlier), which no one seemed to think were repealed by the change in the federal constitution. It was not until the passage of the 14th amendment that the protections of the bill of rights came to be incorporated against the states.
The main purpose of the 2nd amendment was to ensure that states and localities would be able to defend themselves not only from foreign threats when the US army was not able to protect them, but also from the US army itself whenever the Federal government oversteps its authority. States and municipalities owning their own nuclear weapons, or permitting their residents to own their own nukes, would be perfectly in keeping with this purpose.
All federal laws regarding firearms are unconstitutional, and thus null and void. State laws and local ordinances regarding firearms are perfectly fine, assuming they do not violate any provisions of the state constitution, city charter, etc. The 14th amendment's equal protection clause should make it unconstitutional for a state or locality to pass any race-based restrictions on weapons (or anything else) or to prevent citizen's of other states from keeping and bearing weapons on the same terms as is allowed for the locals.