You're kidding, right? Cocaine is legal to own with the right paperwork, but go down to your pharmacy and ask for some. Any restrictions on your legal guns? I thought so.
This wouldn't stop "private transfers" of mags, of course, but you'd never see a hi-cap at a gun show, mail order, online, or in an auction. I would bet that 98+% of mags are bought that way today. The impact of this law is potentially devestating!
-Troy