The real danger is the "Death by a 1000 Cuts": Putting a tax or other restrictions on ammo will put dealers out of business. They've already screwed them over by letting financing companies deny credit to firearms dealers. They can squeeze the market dry within 5 or 10 years without having to pass an actual "ban" and they can avoid the political backlash.
That is certainly a threat.
But with complete control in DC, I fear they may swing for the fences.