The check on violent government overreach are the moral compasses of individual soldiers, peaceful protests and a free media. If we get past all of these things, no "well regulated Militia" is going to stop the U.S. Army. The best chance would be state national guards. My point here is that fully automatic fire, tanks, artillery and air support make any resistance useless. Perhaps a guerrilla war could be fought, but to someone seeking complete control fighting guerrillas is an annoyance, not an obstacle.

This is mostly because the FDA tightly restricts ownership of 'destructive devices', which are the weapons needed to fight an effective war.