What arms are necessary to prevent the establishment of a tyrannical government?
If that's now the reasoning behind trying to get as many Americans armed as possible, we're in major hot water. The US military budget is the largest in the world by far, larger than the entire budget of many other countries (though it's nearly impossible to find out exactly how large it is due to off-budget and classified funding).
If we the people are up against that, the notion of arming everybody in response is a lost cause. A modern army runs on continually evolving (and costly) technology that simply cannot be duplicated by the rabble. ('scuse me, rabble)
A better idea: making sure the military is of, by, and for the people, that members of the military, from the bottom to the top, are sufficiently dedicated to defending the US that they would never turn on their own people, and to their own commander in chief so that we are not at risk of mutiny.
If dissent in the military ranks is truly an issue, the way to deal with it is through established methods of discipline, not by having a bunch of armed civilians run riot and take matters into their own hands.
We aren't Syria, as mentioned a few days ago on this topic. We're an established democracy and the way to keep it that way is to keep our democracy healthy, not fragment ourselves into official and unofficial armed factions so mutually distrustful they're preparing to fight it out.
Because, given the power, technology, and money disparity I mentioned at the top, you know which way that one will go. The indigenous Afghani warriors are tough as nails, have a tribal structure, a brutal enforcement system, and loyalties unparalleled in western countries. They have geographic advantages including mountains so wild nobody knows where the boundaries run, and have been at war against outsiders for generations. They're shaking off the US occupation and will likely go back to whatever lifestyle they had before we arrived. I somehow doubt the indigenous Wisconsin warriors would be similarly effective.
We earlier agreed we aren't at that point yet, and we all hope we never will be. If we start feeling threatened by our own armed forces (not rogue individuals) I'm sure TDPF is not the first place we'll hear about it.