What legal hassle?
Let's see, all the paperwork you have to fill out, the fact that the ATF can come by at anytime...
Nothing's illegal unless you're caught. The best way to not get caught is to keep your %$#! mouth shut. Your buddy hasn't figured this out.
Or doing something else that draws the notice of the ATF or police.
Where will he shoot his unregistered MG? The local rifle range? Hmmm . . .
I always wonder about that. Personnally if I had an illegal firarm I'll make sure I'm not seen in public with it. Then again I wouldn't have illegal firearm to begin with.
-Bill