I was curious about this very thing and wrote to the BATF and this is their reply to me!
- - - - - - - - - - - - - - - - -
Thank you for visiting ATF's Website. As stated on our site, generally, we do not answer technical questions via e-mail, but I contacted our Firearms Technology Branch (FTB) and was advised the following:
"If you have a new Thompson Center Contender frame that has never been made into a rifle, then the frame is neither a pistol nor a rifle frame. At that point, the frame may be legally manufactured into either a pistol or a rifle. If at any time the frame was made into a rifle, the following procedures must be followed:
As you may be aware, the National Firearms Act (NFA), 26 U.S.C. § 5845(a), defines the term "firearm" to include the following:
...(1) a shotgun having a barrel or barrels of less than 18 inches in length; (2) a weapon made from a shotgun if such weapon as modified has an overall length of less than 26 inches or a barrel or barrels of less than 18 inches in length; (3) a rifle having a barrel or barrels of less than 16 inches in length; (4) a weapon made from a rifle if such weapon as modified has an overall length of less than 26 inches or a barrel or barrels of less than 16 inches in length; (5) any other weapon, as defined in subsection (e); (6) a machinegun; (7) any silencer (as defined in 18 U.S.C. § 921); and (
a destructive device. The term "firearm" shall not include an antique firearm or any device (other than a machinegun or destructive device) which, although designed as a weapon, the...[U.S. Attorney General]...finds by reason of the date of its manufacture, value, design, and other characteristics is primarily a collector's item and is not likely to be used as a weapon.
Certain categories of firearms are subject to registration and tax provisions of the National Firearms Act (NFA), 26 U.S.C. Chapter 53. As defined in the NFA, Section 5845(a)(4), the term "firearm" means, "a weapon made from a rifle if such weapon as modified has an overall length of less than 26 inches or a barrel or barrels of less than 16 inches in length." It is unlawful for a person to make or possess such a firearm that is not registered to such person in accordance with the provisions of the NFA.
Making a Thompson Contender rifle into a handgun having an overall length of less than 26 inches or a barrel or barrels of less than 16 inches in length would constitute the making of a weapon from a rifle and, therefore, production of a "firearm" as defined in the NFA. In order for you to make a single shot handgun from a Thompson Contender rifle frame, you need to submit a completed ATF Form 1 - Application to Make and Register a Firearm with the National Firearms Act Branch (NFA), 244 Needy Road, Martinsburg, WV 25405. The application must include a set of your fingerprints, your photograph, $200.00, and you must have the local chief law enforcement official certify that he/she has no information that you will use the firearm for unlawful purposes and that the making and possession of the firearm is not in violation of State law. You must also answer the questions on the form about being a prohibited person. Upon confirmation of registration of the weapon with NFA, you may then make a single shot handgun using a Thompson Center Contender rifle receiver.
Also, we advise that you contact local authorities to determine if there are any State laws or local ordinances affecting this conversion.
We thank you for your inquiry and trust the foregoing has been responsive."
If you have any further questions, please call them on 304-260-1700. Regards,
- - - - - - - - - - - - - - - - - -
I hope this clears it up for you folks!