
I never said anything about banning guns, it’s shifting the tracked component from the receiver to pressure-bearing internals, as should have been the case since the NFA. If anything, receivers shouldn’t even need serialization beyond manufacturer info because they’re the easiest component to manufacture. And if you’re worried about things like accessing quick-change barrels and such, all that would change is adding an ID check if you‘ve already gone through a background check before.
Thats why receivers were made to be the "part that counts as the gun", home manufacture is protected and that commonly included buying specialized parts like barrels, bolts, and other mechanisms. We should not be choosing the parts that are hardest to manufacture and counting them as a gun by themselves specifically to deny this, not to mention legitimate other uses for them.
Even if we did put in a law where you must serialize bolts or barrels or any pressurized material used, people wouldn't obey it. They'd take off other serial numbers that exist, and make parts that never contained them. We see this with receivers already, only difference is what type of CNC is used.
I don’t think that adding an ID check for barrels and/or bolt lugs presents a significant hurdle for law-abiding citizens. Sure, common components such as screws, springs, rails, and pins definitely shouldn’t be regulated and don’t need to be. If anything, it would be the background check system itself that would have to change more than purchasing habits.
Having registered internals could also potentially allow for loosening restrictions on limited commercial home gun manufacturing (in some cases), since if the internals and pressure bearing components are what is registered and matter for reliability and safety, the other elements become less important for qc and liability.
For a large number of firearms (mostly rimfire and handgun calibers), you can just fdm 3d print pressure bearing internals as well nowadays, even the rifling of a barrel can be printed. Regardless, people have been making bolts and barrels from hardware store steel cuttings since modern guns and modern hardware stores with steel cuttings existed.