If those were non registered destructive devices, it would be bad to be caught with them. They were legally sold as shotguns initially, but were later classified as DD's. Complete a Form 4, pay for one, send in a check for a $200 stamp and a 6 month wait, and you can own one.

Here is a pic of one guy's haul.


Notice the old school Winchesters and the Savage 99. He broke even with those three firearms. 5 or 6 pistols. Profit!