Among them is a military M1 Thompson dewat.
DEWAT
Did you guys miss this???
DEWAT (DeActivatedWarThrophy)
IF the gun is ACTUALLY a DEWAT in compliance with Fed regs, then the Fed doesn't give a rat's posterior about it. It's NOT a machine gun, it's not ANY KIND OF GUN.
Its a lump of metal (and wood) that cannot do anything. Period.
Now, the issue becomes, does the Tommygun in question meet the Fed standard to be a DEWAT. Paperwork on this from when the gun was DEWATted would be a big help, and would solve your problem, but if none exists, all is not lost.
Bill has the right answer. Contact an Attorney, and have them deal with the FED on this matter. IF the gun turns out to be a valid DEWAT, the money spent will seem excessive, but if the gun does not meet DEWAT requirements, then it is an unregistered machine gun, and the cost of an attorney to avoid a huge fine, felony conviction and 10 years in jail, is more than worth it.
Basically Fed DEWAT standards mean that critical areas of the gun must be cut open or welded closed, so it cannot be returned to function.
If you can return the gun to function just by replacing parts (anything or everything other than the receiver) its not a legal DEWAT.
Weld barrel shut? Not good enough, because you can replace the barrel and restore function.
Throw away internal parts? Not good enough. Put in more parts and rock & roll (illegally!)
Torch cut / grind the receiver (in the right place) or weld it shut, =DEWAT (as long as the Fed agrees and they generally do, once they have inspected it)
Basically if the level of effort and tools required to restore the gun to function come close or match the level of effort needed to make the receiver from scratch, it will accepted as a valid DEWAT.
However, each case is individually judged. Get a lawyer, have the lawyer contact the ATF for an evaluation of the gun. If the Fed says its DEWAT, you get it back, and are home free, minus the lawyer fee.
If the Fed says no, it's contraband, the lawyer will surrender it, and (likely) you will not be charged, (though you COULD be) because you acted in good faith. On the plus side, if you ARE charged, you already have a lawyer...
Even the "evil" ATF seldom goes after people who are obviously trying to comply with the law. Those who voluntarily come forward seldom get punished, even though they are technically breaking the law.
Those the ATF catches, trying to evade the law, they go after with a full court press.
Like they do with semis that MALFUNCTION and fire full auto. Yes, technically it becomes a machine gun, and you are in violation of the law, BUT, its a malfunction, and the ATF allows for this.
UNLESS you don't get it fixed! (time matters here...) If you keep it, knowing it goes full auto, and don't get it fixed, THEN you are deliberately breaking the law, and when caught, you WILL be prosecuted to the full extent.
Get a lawyer, follow their advice. If you don't like their advice, get a different lawyer and see if they give you other options.
Since the gun is clearly a real Tommygun, AND you do not have papers from the FED proving it is deactivated, the issue is now in question. DO NOT dispose of the gun, or destroy it, that might be a crime (destruction of evidence). Surrender it to your lawyer to hold until the FED determines if it is contraband, or not. THERE IS NO OTHER LEGAL OPTION!!!!
You might consider removing all the parts you can remove, before surrendering it to your lawyer, but I would talk to the lawyer first, and see if there is some reason (that I don't know) not to do this.
I have no idea the value of the DEWAT, but a real Tommygun with FED papers proving it DEWAT, and no longer a gun, isn't a common item, and could be sold to anyone, even in the most restrictive states, because it's a "decorator item" and NOT a gun. Without the FED papers, it could be a felony.
Did I mention, get a lawyer (one who knows what they are doing in these matters)?
I've laid out the options as I see them, I'm not a lawyer, and my advice is worth what you paid for it. If I've made any errors, I will gladly stand correction.
Hope for the best, plan for the worst, and you are seldom disappointed. IF the gun was deactivated in a way that meets the Fed approval, you will get it back. If not, you won't. You MAY get the option to have the DEWAT redone to meet the Fed requirements, but I wouldn't count on that. If the gun fails to meet Fed standards, you might inquire, but don't hold your breath.
Good Luck!
And, please, let us know how things work out.