I fear we could see more of this as Poloticians look for ways to implement stealth gun control and to close their budget gaps. The average citizen might support the 2A, but may not really be concerned about increased taxes on guns, ammunition and reloading supplies.
You are wise to fear it. They can't outlaw firearms but they can make buying them, as well as buying ammo, out of the reach of many people by imposing high taxes on them.
Here is another example of a bullet tax.