ATF Technical Letter About AR Buffer Tubes On Non-AR Pistols

| February 18, 2015 | 7 Comments

Putting an AR15-style buffer tube on a non-AR15-style firearm has always been a contentious topic. I’ve written and stated several times that I didn’t know if it was okay to do or not, despite several retailers and manufacturers putting AR15 buffer tubes on AKs, MP5s, handgun enclosures, and many others. Finally the ATF responded, and their opinion is the typical convoluted mess we’ve all come to expect.

Michael R. Curtis,┬áthe latest Acting Chief of the Firearms Technology Industry Service Branch (among several, I wonder what’s up over there) decreed that

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.

This sort of makes sense, until you consider the order in which people typically attach a brace to a pistol buffer tube.

First the tube goes on the firearm, and then the brace goes on the buffer tube.

According to Curtis’s opinion, doing so in this order could be interpreted as manufacturing an SBR. Given other legislation, once an SBR is assembled, it’s an NFA item until removed from the registry. This further complicates things unnecessarily.

Is someone from the ATF watching you assemble your brace-equipped pistol? No — but this is the kind of illogical thoughtlessness that leads to more confusion instead of more clarity.

I also think this makes for an interesting “race condition,” wherein having a buffer-tube equipped non-AR may be construed as building a firearm, but putting a brace on a pistol and then shouldering it may (according to ATF opinion letters) permanently create an SBR.

We live in strange and interesting times.

Here’s a PDF of the full letter:

atf ak ar15 buffer tube 2015-02-11

Hat tip and thanks to reader Dolomite_supafly for letting us know about the recent letter.

About the Author:

Short Barrel Shepherd Short Barrel Shepherd is a regular guy and works to make Web sites and mobile apps easier for people to use. He spends his free time attending fight-focused firearm, knife, and combatives training, motorcycling, writing, and playing games. His daily carry is a Glock 19 pistol and an AR15 .300 Blackout pistol in a backpack.
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7 Comments on "ATF Technical Letter About AR Buffer Tubes On Non-AR Pistols"

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  1. MwA says:

    I’ve found it interesting that things like the SIG brace have come under majority scrutiny from the ATF lately vs other products…say bump fire stocks. Who knows- maybe they’re next?

    • James B. says:

      I’ve fired an M16A2 on burst and single-shot with a fast trigger finger. You can tell the difference in sound, but the effect is equivalent. If the ATF has similar experience, they may not consider a bump-fire stock worth their time.

  2. David says:

    To be fair, this is probably one of the less offensive rulings by the ATF. You can’t put a stock-like device on a pistol that serves no other purpose than being a stock, use it like a stock, and then claim it’s not a stock. If anything, this is an excellent ruling for the AR pistol guys – they are apparently in the clear when shouldering their buffer tube. (Now, buffer tube COVER… hmm.)

    Also, “once an SBR always an SBR” is more of a statement of faith on the internets rather than the law or a real policy of the ATF. I can slap a 16″ upper on my AR-15 SBR, and the BATFE would very much agree that it’s not an SBR anymore, and that removal from the registry is encouraged but optional.

    • Koyote Tan says:

      I did that very thing with no intention of it being a stock. Their ruling is still convoluted, because they use terms like “may be considered evidence” and “intended to facilitate installation of”. The sights on a PAP M92 are hard to pick up without an index to my cheek, at least for my farsightedness. I permanently attached a StormWerkz mechanism to my PAP M92 for that benefit and that benefit alone, not for an SBR without the stamp. That PAP is now owned by my friend (his first gun, badass) and he has the SBX and the Thordsen Customs cover on 2 different tubes he screws on or off. He doesn’t shoulder it, but found he needed the index too.

      Intention criminalization is slippery law and incompatible with a free society, since intentions are only known by the actor who does or does not reveal them. How can you justly prosecuted for your intentions? You can’t, justly. This is “how can we get ’em today” justice, which is ‘justice” looking for an offense, any offense.

  3. Jim says:

    Could it be possible that this letter, while poorly written, is entirely focused on the fact that buffer tubes on AK’s (and shotguns) are non-functional, therefore are clearly being used to “redesign” the product? This detail would leave AR’s in the clear.

  4. Joshua says:

    The whole thing is mind-numbingly absurd. It is unbelievable how hard we work to follow the rules, and how difficult they make it for anyone to do so. It is really annoying that Mr. Curtis did not specifically answer the questions regarding the addition of a folding mechanism and measuring the overall length of a firearm. One thing that really gets confusing is that while it says “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.” in another recent opinion letter (also by Mr. Curtis) to Thorsden Customs the use of an accessory intended to provide an enhanced cheek weld did not reclassify a pistol as an NFA item. So if a buffer tube is added to a non-AR pistol with the intent to serve as a check weld enhancement, it ought to be good to go; but that is clearly at odds with this most recent letter. Grrr.

    So be on the safe side, it would seem to me that a non-AR pistol can only have a buffer tube installed if it is used in conjunction with either a brace, or a Thorsden/CAA setup. I’ve included links to the Thorsden letters below:

    Thorsden Submission

    ATF Response

  5. Van der Lin says:

    When an item is not configured as a NFA item, it is not under the purview of the NFA. A SBR can be reconfigured as a Title 1 rifle and sold as such w/o any reference to the NFA. There is no legal requirement to remove an item from the registry, it is a courtesy.

    It is not clear to me whether a SBR’d pistol can ever be returned to its pre-NFA configuration and then be considered a title I handgun. I would like to think so but…

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