I don't how relevant this strategy will be in an age of under $1000 desktop manufacturers coming up in a decade or two. They'll be able to do generic strong metal shapes, and after that the cat is out of the bag. Guns are really simple devices that haven't been subject to fundamental innovations since WWI.

The only thing left to regulate would be smokeless powder, and gangs are pretty good at importing various powders with impunity as the drug war has shown us.