We know the Framers of the Constitution intended the Constitution was to be protected by a system of checks and balances... but Hamilton asks in Federalist 28... what if something goes wrong?
It may safely be received as an axiom in our political system, that the State governments will, in all possible contingencies, afford complete security against invasions of the public liberty by the national authority. Projects of usurpation cannot be masked under pretenses so likely to escape the penetration of select bodies of men, as of the people at large. The legislatures will have better means of information. They can discover the danger at a distance; and possessing all the organs of civil power, and the confidence of the people, they can at once adopt a regular plan of opposition, in which they can combine all the resources of the community. They can readily communicate with each other in the different States, and unite their common forces for the protection of their common liberty.
Hamilton is saying the last resort in protecting the republican nature of the federal government lies with the states and their militia. But just because something was published doesn't mean there is any legal mechanism for this. Where was this idea ever written into actual law?
He also writes
The people, by throwing themselves into either scale, will infallibly make it preponderate. If their rights are invaded by either, they can make use of the other as the instrument of redress. How wise will it be in them by cherishing the union to preserve to themselves an advantage which can never be too highly prized!
If in such a battle, is a gun then a vote? Do you want just noble citizens with this vote... this power to restore the nobility of republican government? Or does anyone, be they criminal, drug lord, or sociopath, also have a right to this power?
After all... isn't that where in Hamilton's scenario the original threat to the government begins? With someone who's personal ambition was greater than their moral restraint or respect for republican government... and using the force of arms to impose their will on the nation?
So Gun Nuts... how does your grand theory of the Second work when you find your noble citizens are not just fighting an allegedly repressive government, but also armed criminals, drug lords, and sociopaths who see the conflict as an opportunity? They might even join the forces of repression.
It would SEEM logical for Gun Nuts who believe this Insurgency theory of the Second insist the NRA be more civicly responsible to protect the viability of the armed populace they claim might be necessary to restore government. They can do this by insuring sociopaths, criminals, and those with psychological problems don't have easy access to gun ownership. Yet that's what the NRA apparently wants when they vehemently oppose tightening up background checks. And in the process they threaten the viability of what they claim is the nation's last defense against tyranny.