The problem with 'vetting' is twofold:

1) In order for someone to judge or otherwise assess the quality of work, you would need to find someone who understands what good work is, and isn't. That's getting harder to find as time goes on...and even if you did find a person, or people, to be the judges - who judges the judges?

2) The other fallback would be for the government to establish a licensing process for gunsmiths. Who among us thinks that would turn into anything other than a train wreck and an excuse for the government to collect more fees and taxes?