And how will this be enforced?
Here is a thought.....actually put criminals in jail. That might help.
In principle I think it's a good idea.
I've said it before, any illegal sales of unauthorized firearms, especially to minors, should be prosecuted to the full extent of law and be treated as if it's selling heroin or aiding terrorists with a minimum of 10 years in prison, more like 15 or 20.
However, given the widespread use of guns in the US, this may be extremely difficult to enforce.