Imagine the unthinkable, Congress & Senate fail to act and Comrade Obama passes an unconstitutional gun grabbing order. Even if the entire military followed orders, every cop, and other Law Enforcement Officer followed the orders what will happen.
America has been one conflict or another since World War each decade leading up to present. Hundreds of thousands of Veterans have returned to their civilian lives, all trained killers with the necessary skills and training to wage war. Most are armed, and nearly all will grab their guns and shoot anyone who would dare attempt to do something so foolish as take them away.
It will be a blood bath of epic proportions, police and local law enforcement will die in droves, entire communities will become lawless as the police are decimated In reality, most police will quit out of honor and duty or for fear of dying or their families becoming targets. Of the ones who do decide to stay, their families will become targets, their homes will become their graves. They quickly go from being hunters to the ones being hunted.
Raids, sniper fire, and assassinations will become common place, not to mention the demands of law enforcement. Gang activity will increase, as well as general lawlessness. Police forces will be stretches thin at best. Even if national guard is mobilized and report for duty, their numbers will be low at best, their families will be targets as well. Politicians and their families will assassinated in droves, either for not perceivably doing enough or being part of the Gun-gran. Anti-gun celebrities will be targets, some if not most will end up dead before the conflict is over.
Martial law will be declared food, gas and medical supply shortages will become common place. A black market will popup overnight. As food becomes scarce and police forces ae further spread thin, more people will die. Gangs will dominate large areas of the country, rape gangs and looters will become common place. The power grid will be offline in many areas of the country. Widespread famine and disease will be common place.
Inevitably One or more higher ranking Military forces will break ranks throwing their might against the new Unconstitutional Gun-Grabbers. The biggest wildcard will be the states with nuclear silos, and the nuclear arsenal thats scattered across the Armed forces. One or more population centers may be targeted by nuclear devices
Foreign governments will send agents and resources to both sides to fight a proxy war for the soul of the nation. The nation will be fractured, and whom ever wins the battle it will be a great cost, 50-100 million dead, and the horrors of war will haunt generations to come. Any politicians & celebs who fled before the conflict will be hunted down after the dust has settled and killed should they of had an public voice against the winning political factions beliefs.