A Class III stamp from the U.S. Bureau of Alcohol, Tobacco and Firearms (ATF) permits a qualified citizen to purchase Class III firearms restricted under the National Firearms Act (NFA). These firearms, which can't be transferred without the Class III stamp, include machine guns, silencers, short-barrel shotguns and short-barrel rifles, manufactured before May, 1986. Purchase of these weapons requires fulfilling a variety of ATF requirements for issuance of a Class III stamp and advance payment of a Class III tax of $200.00.
Verify in advance that you will be able fulfill all requirements for the Class III stamp before disbursing any money as part of a restricted firearms transaction.
Make sure you are older than 21 years of age and have no felony or violent misdemeanor convictions and no dishonorable military discharge.
Consult with your local Chief Law Enforcement Official (CLEO) such as police, sheriff's department or district attorney to verify in advance their policy regarding signing your ATF Form 4. Signature is at the discretion of the local CLEO, and some officials have a policy to routinely decline all requests. The Bureau of Alcohol, Tobacco and Firearms will not issue a Class III stamp without a local CLEO signature on Form 4.
Pay in full for the firearm at the Federal Firearm License-holding dealer from where you wish to purchase. The dealer will supply the ATF Form 4 and two FBI FD-258 fingerprint cards.
Fill out the information requested on both sides of ATF Form 4.
Obtain two passport photos, and attach them to ATF Form 4.
Take ATF Form 4 and the fingerprint cards to your local CLEO, and request a signature on Form 4. Also, request to be fingerprinted by the CLEO.
Send two copies of Form 4 with passport photos and the fingerprint cards to the ATF address shown on Form 4. Also include a check or money order to pay the $200.00 tax for the firearm you are purchasing.
Fill out ATF Form 5330.20 Certificate Of Compliance to attest that you are a legal citizen and mail it to the Department of the Treasury at the address shown on the form.
Wait up to 120 days for the background check and processing to complete. When you receive the certified copy of Form 4 with the Class 3 stamp affixed, present the documents to the dealer and take possession of the firearm.