What the 2nd does do, is keep things like police-state door-to-door roundups and executions from happening. They won't do that if they know people can and will shoot back. We've already seen in the middle east (and before) how a giant and well-armed military can be held back by a small and determined group of fighters. At the end of the day, even for all the technology, wars are still won by men on the ground with rifles. (Shotguns and handguns don't cut it, they aren't effective over long distances, and most real life battles take place over 100+ yards, not in Call of Duty-esq tiny maps.)
No. That's a pure fantasy. There is a well-known fact that during Stalin's regime many homes had guns. ESPECIALLY rural homes where millions were taken and executed. Village people always had guns. And their guns did not matter. Guns don't matter when people around sit and pray that police is not after THEM and hope that they will arrest somebody else today. And may be tomorrow.
That's how totalitarian state works. Guns don't not matter, alas. Funny thing, it was easy to obtain a shotgun or a rifle during soviet time, only hunter's paper needed and it was easy to get. They begin to restrict guns heavily during 80s and placed insane restrictions during last 20 years.