Truth be told in a scenario of a real red/blue civil war, our current Armed forces would be irrelevant. If you scale up the last Civil War to today, each Army would have 6-8 MILLION men in each, which would dwarf current force structure.
But I think that kind of action is academic when you have tens of millions of civilians, who look and act like all the other civilians, serving tea and coffee and every other supply under the sun to the gov forces. I think their supplies would begin to run short rather rapidly and what they did get would be a mixed-bag Russian roulette assortment of goods.
I think life in the military would lose its appeal when a goodly number of guys started getting letters from home that said "Don't ever come home. I mean it! Love Mom and Dad."
Despite all his bravado, the despicable little toad who crapped this Kill-'em-all-for-Obama piece of verbal excrement didn't even have the courage to leave it posted.
It'll be ignorant jackasses like him who start the war, but it'll be the tens of millions of God-fearing, Constitution-respecting well-armed Americans he fires on who will finish it.
A little math might be illustrative. In my state (WA) there are about 6,000,000 civilians and 8,000 guardsmen. Given a 6 hour sleep rotation, that leaves 6,000 guardsmen at any given time. That's a 1000:1 ratio of civilians to guardsmen. Draw what conclusions you will.
In order for active duty personnel to become involved, you'd have to have a multi-state, full blown insurrection. Then the ratio decreases, but is still very large.