No offense, but you clearly don't know what you're talking about.
First, one redneck with a gun is not the situation I'm describing. I'm talking about 265 million guns, half of which are owned by 3 percent of the 242 million adults in the US. I'm talking about the guy who can literally arm a squad of guys from his basement. That's the guys I'm talking about. Not the guy with a .50 cal, who by the way probably isn't a redneck in the trailer park because that's a $10,000 gun that shoots $5 rounds. A much better example would be the field of deer rifles that can pierce bullet proof vests with Wal-Mart ammo costing 50 cents a round out of a $400 gun with a $400 mil dot scope. I'm not even an amazing shot, and I know for a fact that I've hit a deer's heart when I was amped up with adrenaline, on the spot for time, unexpecting anything, and the deer was so far away I had to check for antlers in the scope to make sure it wasn't a dog. And there are plenty of 'rednecks' who know this very common ammo can also penetrate body armor.
Second, over and over running through history are examples of lesser armed military's and guerilla groups defeating larger and more powerful millitaries. Guerilla tactics, including selected assassinations, IEDs, stick-and-moves, etc. have long been effective. You think the US military doesn't outgun the Taliban? I've spent hours in nasty planes with nasty guns overhead watching and waiting for the Taliban to do something while they just waited for us to leave. Partisans in the Spanish Civil war took out bridges, ISIS gained tanks and anti-aircraft weaponry, took over Iraqi bases and armories. It happened not some far off and long time ago, it happened last year.
These guys are already well-armed, they are more knowledgeable than you give them credit for, and they would quickly arm themselves with better equipment. As well, you discount the very real possibility that many of them either are currently, or have in the past, in easy access of military equipment. Perhaps they are in the National Guard in Kentucky where there are huge amounts of surplus tanks, or near Herlong, California where there are thousands of mothballed and ready to go M1A1s. You can't just assume that some General would have the final say over what happens with his base. He is heavily outnumbered and one Colonel in the ranks that takes forces for some rebels can completely change the balance of power.
The point is, you can start with a gun. A single bullet in the right/wrong person's hands can change the world.