It would be over in less than 24 hrs. They don’t have the firepower nor the training to stand up an effective fighting force. Their only prayer, is that the military sides with them and that’s not happening.
The US militarily is minuscule and irrelevant against a general insurrection. 500,000 active duty is a drop in the bucket compared to millions upon millions that can muster in an emergency.
In a real CW scenario, they'd by outnumbered by a series of magnitudes and completely overwhelmed by shear numbers in the opposition.
Btw, there on more trained veterans on the streets of the U.S., than exist in all the services.☺