If anyone happens to find a WWII bringback MG there is a chance it was registered and can be legally transfered.
First look for *any* paperwork concerning that gun. Look for forms from the ATF or even from the IRS from "way back when."
You can also look for "capture papers" from the military from when the gun was brought home. There have been a few sucessful cases where the presence of capture papers was used as evidence that the government "registered" the gun and thus the gun was legal.
(If you go that route though, you'll need to find and hire an attorney familiar with the ATF rules regarding full auto weapons. That's not an argument I'd try to make on my own. You could find someone knowledable through Bower's board at
www.subguns.com).
If you can't find *any* paperwork then have your attorney contact the ATF on your behalf to see if the ATF has a record of the gun in the NFA registry. If the ATF does have a record that the gun was registered, then it's relativey straightforward to get it transfered to a new person.
I'd have an attorney contact the ATF though because then he could arrange for the legal surrender of the gun if no records are found.
If you do have to surrender the gun for destruction you can dissassemble it completely first. The ATF requires that the receiver be destroyed with a certain method, but the other parts are legal.
A "parts kit" from a WWII Thompson, or a MP-40, or a MP-44, or whatever is valuable in itself. So, if all else fails, I'd surrender the receiver and keep the parts kit to sell. Of course, if you surrender the whole gun, don't expect to get any parts back.