Several people, including Justice Scalia, have raised the question of what good small arms would be against modern forces, and this is a good point, but it overlooks something. Citizens with small arms might not be able to best a technologically sophisticated force, but they could certainly make themselves ungovernable, and that's a good start.
As for where to go from there, it seems to me the matter would hinge on appropriating the sophisticated weapons and persuading your opponents over to your side. Mao was good at these tricks. I detest the politics he stood for, but he had some good ideas about how to wage war. (He lifted a number of them from Sun Tzu.)
God grant this question forever remains a hypothetical, in America, and no need to test the theory arises. And yet the Second Amendment may head off the possibility of domestic tyranny by its mere existence. If the tyrant wannabe knows Americans are able to shoot back, it may complicate matters sufficiently to make him reconsider his plans.
A more likely scenario for widespread militia action is in cooperation with the "regulars" (U.S. soldiers) in case of some kind of internal emergency. I hope that doesn't happen either, but in such a case, the citizens' small arms could do a whole lot of good, for you can never have too many riflemen.
Back to the Chinese revolution; I wonder if the thing would have happened at all, if China had posessed a robust tradition of the kind our Second Amendment reflects. But I'm sketchy on the details here. Can somebody fill me in on private arms ownership in the Republic era (1912-49)?