The AR-15 buffer tube is the universal attachment point for aftermarket stocks. Just about everyone makes an AR-15 compatible shoulder stock, and even newer piston-driven guns that don’t need a buffer are being designed with an adapter to allow the use of existing stocks. For those with firearms like AK-47 pistols, adapters are available to allow you to mount an AR-15 buffer tube so you can then add an AR-15 stock or brace to your gun if you want. According to a new letter from the ATF, though, it appears that bolting a buffer tube to your AK-47 pistol might now be considered “manufacturing” a short-barreled rifle, and therefore illegal without a tax stamp . . .

A petitioner to the ATF wanted to know the answer to a smattering of questions about the legality of various configurations of firearms, but the lead-off question is probably the most important. They wanted to know whether adding a buffer tube to an AK-47 pistol would constitute the manufacture of a National Firearms Act regulated item, specifically a short-barreled rifle.

The ATF responds:

The buffer tube on an AR-type pistol serves a legitimate, vital function in the operation of the weapon system, and is not considered to be a shoulder stock. In contrast, a buffer tube or receiver extension is not designed or intended to be attached to an AK-type pistol; instead, it is designed and intended to facilitate installation of a shoulder stock. Use of a buffer tube on an AK-type firearm that has no use for such an item may be evidence that the weapon is intended to be fired from the shoulder. Therefore, adding a buffer tube to an AK-type pistol, where the barrel is less than 16 inches in length, would result in the manufacture of a “firearm” as defined in 5845(a)(3). However, if an AK-type pistol were to utilize an AR-type buffer tube to facilitate the attachment of a (sic) SB-15 stabilizing brace accessory, a “firearm” as defined in 5845(a)(3) would not be made and consequently lawful to possess.

I smell a whiff of common sense and logic, but there’s also a strong overtone of WTF. The ATF says it’s OK to attach a buffer tube to an AK pistol if you then immediately attach an SB-15 stabilizing brace to the gun. It’s still a pistol, since it was designed and intended to be fired with one hand as a pistol legally should. But that creates an interesting legal situation.

When you have your AK-47 handgun, everything is OK — it’s a handgun. When you attach your buffer tube, it magically then becomes a short-barreled rifle. Because obviously that buffer tube serves no other purpose. Then, when you slap an SB-15 brace on it, all your sins are forgiven and the gun once again becomes a handgun.

As Alex Bosco, CEO of SB Tactical points out, there’s a legal sequence required. FIRST you have to put brace on the buffer tube and THEN put the brace-equipped buffer tube onto the firearm. If you put the buffer tube onto the pistol first and THEN attach the brace, you have created an NFA item – however momentarily (as per United States vs Thompson Center Arms).

That may somehow make sense from the ATF’s perspective, but in terms of practical usage there’s a little bit of confusion. Do you need a tax stamp to transit through the NFA-regulated middle position of an AK pistol with a buffer tube on you way to a pistol? How about if you intend to use the buffer tube as a chin weld device, which is perfectly OK? As always, there are more questions than answers.

Anyway, good news: the ATF officially consider the SB-Tactical brace legal. Chocks away!