Blah blah blah, its only illegal if you get caught.
I'm not so sure about that law anyhow b/c I've purchased a sawed-off shotgun from a pawn shop, twice (once in WV & once in NC) without any special permission from the goverment (God knows you have to ask them to do anything anymore & they still sh!t all over you). The way it was explained to me, by a man of the law no less, was that if the shotgun is manufactured from the company it's registered a certain way but you can sell, posses or purchase a "modified", and I use the phrase lightly, one legally so long as you are not caught making the "modification" without all of the hoops & extra sh!t. Oh & without them knowing what you have in your household no less (they don't need to know anyhow).
Anywho, I'm not worried. Law enforcement & goverment have no need to "come into" my domain. I'm not out killing or robbing or gang bangin' with any weapons I have so who cares what I have. Hell I pay my taxes, I support a couple hundred people on Wellfare from my hard earned money alone; I don't cheat, steal or molest the system (and what a sh!tting one it is too), so all I ask is to be left alone.
Sorry to highjack by the way