There is no way that the weaponry available to the general population is going to be able to hold off the government. It's an outdated concept that has no practical application, only catering to that big old gun fetish.
What are you talking about? This isn't a yes/no thing, it's a proportions thing.
In any given rebellion, you're going to have:
1) Some proportion of the population actively rebelling
2) Some people who don't fight / don't offer much help to anybody
3) Some loyalists who will actively side with the standing government
The better armed the civilian population is, simply the lower the relative advantage group #1 can have and still succeed, versus a less well armed population.
For example, if there were no military at all, then all other things equal, you'd expect a rebellion to succeed with a 51% ratio of group #1:#3
With a military, rebels have to have a larger proportional advantage to compensate for the more prepared and trained standing army. But there's always an upper limit, because at the maximum 100% group #1:#3 ratio, the government obviously couldn't ever win, since they'd have zero supply lines with no civilian support (and most of the soldiers would be defecting as well)
So the reality is always
in between those two extremes somewhere. And wherever the magical number might be right now for any given proportion of the population in revolt, it moves up by some amount, in a
continuous, incremental fashion, as citizens get more modern armaments, and it moves down in a continuous fashion as they get fewer and more outdated armaments.
Generally, I would suspect that most Americans would
want the ratio to be somewhere much higher than 51% (unstable) but also much lower than 100% (implying completely unsupported totalitarian reign of horror). And at the same time, we want to balance not too much crime. So there's a balancing act in there, and everybody simply has different opinions, but it all MATTERS.