So the "loophole" is really just the fact that gun owners are exercising their 1st amendment rights along with their 2nd.
I have sold a few guns in parking lots - which is legal in my state. So that would be a marginal pain next time I want to change things up, but I'd still give them that - and the mental health reporting - over restrictions on what I can own.
Whether you agree with it or not at least those restrictions follow some sort of logic. As long as he didn't look suspicious a criminal in my state could buy pretty much any gun he wanted via the classifieds. My state also has very little gun crime, so I don't think it's an issue, but at least I can follow the line of reasoning.
Banning semi-autos with a pistol grip on the other hand....... not so much.
si vis pacem para bellum