The goal for me is to restrict the lethality of guns. If we can do that, everyone wins. It's compromise. I think it's possible to modify ammunition so that people retain the right to defend themselves with guns, but give up the "right" to have the capacity to instantaneously kill another human being with a gun. This is compromise. This is what reasonable looks like. And it seems to me, that this solution is far more realistic that mandating everyone turn in their guns or whatever.
i don't think you'd have a chance in hell at eliminating a black market in lead bullets, or even making that market difficult to access. i don't understand what you'd plan to do about hunting ammunition, or how you think you'd restrict it hunting use.
i think you could do something like, make it so that people that fire lead ammunition in self-defense are charged with murder, or at least voluntary manslaughter, while people that fire your rubber or plastic bullets can't be charged with anything worse than involuntary manslaughter, if they happen to kill someone in self-defense.
i guess i don't see it as very useful, or important, of a point because i don't think that many people have guns primarily for self-defense. and those that do, like, they need to buy ammo once every century or so, right?
finally, i think you'd be surprised by how much pushback you'd get from people that do keep guns for self-defense.