I am suspicious of folks who think that an armed populous is not a check on government actions. I would agree that it is not in of itself sufficient, but might very well be a necessary condition in such a large spread out country.
Note that the following comes from the left, the group (within the United States) that at one time was the most likely to be providers of revolutionary violence.
Modern Violence, Resistance and the Calculus of Revolution
Ian Welsh, 6 November 2013 (hat tip: NC)
Guns alone mean little.
America’s founding fathers wanted Americans to have guns and be in well regulated militias. In this, as in many things, they were wise. A militia, properly oriented towards the community it serves, is an organized body of citizens who have military training and are used to fighting as a group. They have ties to the community, and there is not more than one militia per community, they also have ties to whatever local government exists. If enough of these militias decide, as groups, to resist the government, they can do so.
The Arab Spring events indicate that you don't need violence to have a successful revolution. The only problem with this thinking is that everywhere that the military decided to put down the revolution, they either put it down, or it collapsed into a bloody civil war. Weapons in the hands of the revolutionaries didn't create victory, but they did allow them to stave off immediate defeat.