For a long time, I've been thinking with more privately owned guns than people in the US, the genie was out of the bottle and enforcing gun safety almost impossible. Must be millions if not 10's of millions of semi-automatic killing machines in private hands.
But isn't it possible to make it illegal to manufacture the bullets that fit current guns, and force gun manufacturers to produce guns that fire a slightly different caliber bullet. I doubt the current Supreme Court would let that slide. The legal argument in favor of my proposal would be that the Feds and states are determined to make sure that guns are part of a well-regulated regime of gun ownership. Maybe to buy a new gun that fits the new bullets, you need to join a well-regulated state militia (see below).
But it would be something if the US could start over with no private gun ownership, and from then on ban all military-style rifles, large clips, make each gun owner register their firearm and pay a registration fee (as we do with cars), maybe require gun insurance, limit gun ownership to no more then 3 per person/5 per household, take gun safety and training courses, perhaps join a state militia, require state and national background checks maybe including interviewing the neighbors and workplace. New guns could be restricted by fingerprint locks, all have markings to identify the bullets/casings shot form them, new bullets could be intentionally designed to be less lethal (lower velocity, etc).
In other words, with a little a little creativity the US could significantly reduce gun ownership by eliminating the ammunition for current weapons. You don't have to confiscate guns, just render them obsolete. Then begin again with a new regime of gun safety, allowing folks to have guns for self-protection in their homes, and hunting, and no more.
It's also a proposal so that if the 2nd A could be repealed, there's a method of disabling the current guns.
It's a radical idea, but the problem of gun violence and gun fetishism is so gross that creative and bold ideas are needed.