Not civil war, but a revolution. The 2nd amendment isn't worth much except as a very last resort, when the vast majority of people are willing to die to overthrow a government, as we're seeing in Iran.

The people claiming that having guns won't save you against the weight of the army are only partly correct. Having a few guns won't save me personally. I would certainly be killed on my own. But no government can kill everyone, either as a practical matter, or simply because you still need folks to produce the food. When everybody is armed, the government simply cannot oppress them to the same degree.