All this conversion stuff had my head spinning. I decided to call Mech tech and discuss my concerns with them regarding the NFA stuff in relation to their uppers.
I asked them if I had to register my handgun as a SBR in order to be able to put one of their carbine kits on my Glock Frame. They said NO. I asked them about the legality of putting the Glock back to it's original configuration. Their reply was THIS:
Originally Posted by Mech Tech via phone.
What you have is a Pistol. It was manufactured, or imported, and the appropriate tax has been paid by the manufacturer or importer. You are allowed to put any barrel you want to on your pistol. You can make it longer, or shorter, or even change calibers.
"Adding a shoulder stock to a pistol is a fine, AS LONG AS THE BARREL IS at least 16" when you put the stock on it.
Therefore, any end user can convert a pistol to a 16" carbine using any kit they want to AND BACK. No NFA registration, no ATF concerns."
I talked to ATF's NFA branch. He looked up the ruling and emailed it to me. The ATF position is this:
Originally Posted by atf Ruling
The Gun Control Act of 1968 (GCA), 18 U.S.C. § 921 (a)(7), defines the term “pistol” as: A weapon originally designed, made, and intended to fire a projectile (bullet) from one or more barrels when held in one hand, and having (a) a chamber(s) as an integral part(s) of, or permanently aligned with, the bore(s); and (b) a short stock designed to be gripped by one hand and at an angle to and extending below the line of the bore(s).
Additionally, § 921 (a)(7) defines the term “rifle” in part as a weapon designed or redesigned, made or remade, and intended to be fired from the shoulder....
Further, the National Firearms Act (NFA), 26 U.S.C. § 5845(a), defines the term “firearm” to include: ...(3) a rifle having a barrel or barrels of less than 16 inches in length…[and] (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....
Research by FTB indicates that the CCU consists of one of three shoulder-stock variants and a replacement barrel of 16-1/4 inches. (Please consult our enclosure of two pages containing data and images obtained from the Mech Tech Systems, Inc., web site.) The conversion unit is designed to work with either a 1911-type pistol or a Glock-patterned pistol, converting either into a “rifle” configuration. The conversion kit itself is simply a collection of firearm parts not regulated under the GCA or NFA.
As you can see from the citations noted above, there is no definition of a “weapon made from a pistol.” Thus, converting a pistol into a rifle using the CCU would not be a violation of the GCA or NFA. However, there is a definition of a “weapon made from a rifle.” Therefore, when you convert a pistol into a rifle, it can not then be converted back. Doing so would constitute the making of an NFA-class firearm that would require prior approval by ATF and appropriate registration.
So, even though Mech Tech's telephone advice says it's okay, THEY'RE WRONG. Ask them for the ATF RULING, and you'll get crickets. Call the ATF directly, and they send this ruling. This is a ONE WAY CONVERSION, unless you file a Form 1 for your GLOCK/1911 to make it a SBR.
Buyer Beware, and remember, ALL NFA RULES APPLY.