I found a few facts at the Idaho Automatic Weapon Collectors Association
http://iawca.org/mgfaq.htm
Q- What is the procedure for buying a machine gun legally?
A- In general, the buyer must have a clean record with no felony arrests or convictions and no record of violent crime, and in particular no record of firearms law violation. The Bureau of Alcohol, Tobacco, and Firearms (the "B. A. T. F. ") requires background checks on persons with drunk driving arrests on their records, as many arrested for D. U. I. are also charged with firearms violations due to an illegal firearm in the vehicle at the time of arrest. Specifically, Public Law 90-351 (18 U. S. C. , Appendix), Chapter 44 and Title VII prohibit the following persons from possessing a firearm as defined in the National Firearms Act:
(1) fugitives from justice (any crime);
(2) persons under indictment for or convicted of a crime
punishable by imprisonment for a term exceeding one year;
(3) narcotic addicts or unlawful drug users;
(4) mental defectives, mental incompetents, or those who
have been committed to a mental institution;
(5) veterans discharged under dishonorable conditions;
(6) persons who have renounced their U. S. citizenship;
(7) aliens illegally or unlawfully in the U. S. ; and
(8) persons under 21 years of age.
First, discuss with the dealer what types of firearms are available and select the particular one which is right for you and which you want to add to your collection. Idaho Automatic Weapons Collectors' Association dealer-members are knowledgeable and experienced with the many types and variations of machine guns and other N. F. A. firearms which are available to buyers. When you have made your selection and negotiated the purchase price, expect to pay at least a 50% deposit, and possibly a larger deposit if the dealer will be special-ordering the gun for you. Expect to forfeit a part of your deposit if you get "buyer's remorse" and decide to cancel your order. If for any reason the B. A. T. F. does not approve the transfer of the gun to you, most dealers will refund the major portion of your deposit and retain a handling charge to compensate them for the paperwork involved and for holding the gun off the market.
Second, your I. A. W. C. A. dealer will ask you for 2, passport-style photos and information about yourself necessary for the transfer of the gun. He will assist you in preparing the B. A. T. F. Form 4, Application for Tax Paid Transfer and Registration of a Firearm, and the F. B. I. fingerprint cards. You will state that you have a reason to own the firearm, such as for sport or competitive shooting, investment or collecting. He will also put you in contact with the chief law enforcement official in the jurisdiction where you live, whom you will ask to sign the Form 4. After the paperwork has been completed, you will pay the dealer the $200 Federal Tax. He will then send the completed forms and the tax to the B. A. T. F. in Washington, D. C. You will be notified when the Application for Transfer arrives at the B. A. T. F. Approval typically takes 12 to 16 weeks, although it can take up to 6 months in some cases, and the B. A. T. F. will notify you and your dealer of the approval.
Third, when the approved Form 4 is returned to the dealer, you can pick up your gun. Make an appointment with your dealer, and plan to spend an hour or so. You will need to complete the Form 4473 required for all firearms transactions, and you should spend some time going over the features, operation, maintenance, and safe handling of your gun.
You do have to send in a form also if you plan to take the gun out of state.
I would love to get one, however the price of the guns are too steep for me... . Maybe i'll just get a suppressor instead!