That’s a big philosophical argument there.
Historically, it covered the private ownership of armed warships and artillery. That’s pretty expansive.
I would argue that the 2A does not extend to arms that are directly used as an expression of sovereignty or political authority. This would be your WMDs which are primarily about foreign policy, a power that is legitimately ceded to the federal government in the constitution.
There is little other regulation that is constitutional. I think you can make a case for a licensing system for arms that are dangerous by their presence without human intervention. This would cover your radioactive ammunition. IE, a rifle sitting on a table and no one touching is incapable of causing harm, and safe handling requires no special technical knowledge.
Radioactive ammunition is harmful by its unattended presence, and would require specialized technical knowledge to handle it properly.
This leaves a lot of stuff unregulated. Belt fed MGs, shoulder fired anti tank weapons, portable surface to air missiles, and field artillery to name a few. I don’t see this as a problem. Most of that stuff is incredibly expensive; the only people who would buy something like that would be rich people for the occasional lulz. Those people aren’t a threat.
“I would argue that the 2A does not extend to arms that are directly used as an expression of sovereignty or political authority. This would be your WMDs which are primarily about foreign policy, a power that is legitimately ceded to the federal government in the constitution.”
That’s a good point. I hadn’t heard that argument before.