ATF Guidance: Measurement of Pistols

Posted by Kris Vermillion on 2 months ago
ATF Guidance: Measurement of Pistols

The ATF has announced new guidance on how it will determine the overall length of AR pistols and what does or does not enter into NFA territory when is comes to pistols utilizing a stabilizing brace along with other accessories. This guidance comes after a lot of quesitons as to when you could or could not put a vertical foregrip on an AR pistol. Those questions were hard to answer without direct guidance from the ATF as to how exactly the overall length of an AR pistol should be measured.

Adam Kraut from the Gun Collective is a firearms law attorney, and he has a fantastic post and video that help clarify all of this.

Adam writes:

"Based on the letter, ATF is taking the position that because a stabilizing brace is not an integral part of the firearm, it is not relevant to the overall length measurement. This interpretation opens a number of people up to potential issues of running afoul of the National Firearms Act (“NFA”), particularly those who have built AR or similar style pistols which have a stabilizing brace and vertical foregrip."


Shooters looking to place a vertical foregrip on their AR pistol are okay to do so as long as the overall length of the pistol is greater than 26 inches. Nothing has changed about that except the very important aspect of how exactly the ATF will be going around measuring everyone's AR pistols. Personally, I am trying to run down some 26" calipers to make sure that when I measure the bureaucratic infringement on the 2nd Amendment I did it as accurately as possible. But I digress.....

Here's Adam's full explanation which is a must see if you plan to build or are currently building an AR pistol.

But in case you're reading this while sitting on the couch at some boring family function or in a conference room listening to some guy drone on and on about all the work he can't wait for everybody else to do, read Adam's thorough rundown over at Recoil, and make sure you don't go throwing any vertical foregrips onto your pistol without understanding the potential ramifications.


Here's the ATF Guidance in full:

Dear [Redacted],

This refers to your correspondence to the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), Firearms Technology Industry Services Branch (FTSIB), in which you ask about the correct way to measure a firearm equipped with a “stabilizing brace” and a folding adapter.

Consistent with the stated intent of the inventors, and as supported by the objective design features, FTISB has previously determined that “stabilizing braces” may be assembled on firearms as accessories designed to assist with the operation and use of certain pistols or firearms by aiding the shooter in stabilizing the firearm when firing. In contrast to stocks on rifles or shotguns however, such “stabilizing braces” are merely accessories and are not relevant to classification of a “pistol” under the statutory definition. That is, a folding stock on a rifle or shotgun is included in overall length measurement because the firearm must be “designed or redesigned, made or remade and intended to be fired from the shoulder” to be so classified. The stock is therefore an essential element in the statutory definition. Conversely, it is inappropriate to include a folding “stabilizing brace” accessory in the overall length measurement of a firearm because, unlike a rifle or shotgun, a stabilizing brace is not an element of either a statutory or regulatory definition of any firearm. Therefore, when a device operating as a stabilizing brace is attached to a firearm via a folding mechanism, overall length is measured with the brace in the folded position.

Makers also create an artificial overall length measurement by attaching a folding stabilizing brace. Such a measurement would be problematic because the firearm could avoid classification as an “AOW,” yet retain the concealability and remain fully functional. Measuring a folding (or telescoping) stabilizing brace would therefore undermine the comprehensive statutory and regulatory design of the GCA and NFA. As stated above, this is not the case when measuring rifles or shotguns because the statutory definitions include the stock or shouldering device which therefore must be considered. The measurement of a folding or collapsible stabilizing brace in the overall length of a firearm creates an artificial overall length that would permit a maker to avoid classification as an NFA “firearm” without a viable design purpose or legal justification.

Even if stationary however, only standard receiver extensions will be considered in overall length measurements. For example, accessories (extensions) that have superfluous material are not included in the overall length measurement because they are intended to circumvent the law and serve no purpose in the function of the firearm.

Finally, any conflicting information to the guidance provided in this correspondence is hereby invalid and rescinded, if not issued from the Firearms and Ammunition Technology Division, the only ATF Division delegated the authority to provided [sic] technical guidance such as this.

We trust that the foregoing has been responsive to your request for clarification. If we can be of any further assistance, please contact us.

Sincerely Yours,

Michael R. Curtis

Chief, Firearms Technology Industry Services Branch

About Kris Vermillion

About Kris Vermillion

Kris Vermillion is a lifelong shooter who focuses his training on defensive shooting techniques and the shooter’s mindset. Kris works with the Palmetto State Armory E-Commerce and Marketing teams.