Sadly, the idea that millions of Americans, armed or not, would rise up against tyranny is a romantic pipe-dream. The present-day American isn't like the revolutionaries of Lexington and Concord, he's a docile, overfed sheep. Way back in the 1920's, H.L. Mencken saw that we were already headed down this sorry path:
"I am still so young that my toupee looks natural, yet I can remember when, if ordered to toe a mark or climb astraddle upon a rail, the Americano would resist with harsh words, and even with his fists. Now he leaps to position like a well-trained circus horse." ("Traffic," 1925).
This syndrome has only gotten worse. Take away the Proles' shopping malls and SUV's and Monday Night Football, and
then they might revolt, but I still doubt it.