Most likely, martial law will be declared and roads blockaded with checkpoints. So no one will be able to go anywere witout a pass (or a bribe). The Federal Government operating at its usual level of efficiency will really muck things up. There will be arbitrary seizure of property, etc.
“martial law will be declared and roads blockaded with checkpoints. “
That would be a lot of troops. Where do those troops come from?
By the time that happens, (checkpoints searching for firearms), vigilante action will already be underway.
The vigilantes will consider anybody searching for firearms to be just one more set of enemies to shoot at. A checkpoint can’t protect itself from sniper attack without a vast ring of counter-snipers, UAVs overhead, etc.
That kind of manpower simply does not exist.
As the British Army how things went after they were initially welcomed with open arms as peacekeepers by the Catholics in Norther Ireland in 1969.
As soon as the checkpoints went up, the real war began.