ATF Guidance: Measurement of Pistols

Posted by Kris Vermillion on July 9, 2019
Posted in: News & Releases
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.

2 years ago at 7:50 AM
I have an Angled Foregrip on my AR Pistol. It is not classified as a vertical foregrip. Is this a pistol or an AOW ?
Joseph Campbell
2 years ago at 10:04 PM
This only refers to vertical foregrip so I'm pretty sure the angled grip is okay. Please do not write to the ATF asking for clarification. Nothing good will come from it.
2 years ago at 4:52 PM
Yes, please don't ask questions that you probably don't want to hear the answer to.
2 years ago at 6:07 AM
don't put vertical grips on pistols. ANY pistol. even an AR pistol. just don't. this \"guidance\" can change 10 seconds from now, and they won't warn you, just bust you. what part of this are people not getting?
2 years ago at 6:29 PM
A non accountable \"unelected\" federal appointee runs a agency funded illegally with tax payers money presumes to infringe on our right to keep and bear arms with illegitimate regulation. And here, on a presumably pro 2nd Amendment website, we're talking about the intricacies of measuring our personal arms so as to comply? Sorry. I can't do this. Fuck that noise Why the Hell can't you people grow a pair and stand up for yourselves? This is ridiculous and you people are just giving away what our founding fathers fought and died, risked everything for. This kind of thing is our generations Hitler. And you're dropping the ball for all future generations. I spit on you.
2 years ago at 12:18 AM
All shity attitudes aside until the powers to be start respecting the Second Amendment like they do the First Amendment you'll need to pay attention to the crap regulations they're talking about or risk becoming a convict it's your choice dude, that's why it's important to vote and I've been putting up with this crap from the ATF since the mid 60s!!!%
Scot Mckay
2 years ago at 4:30 PM
A gun is a gun what difference does it make what it looks like! Simple logic of which there is no longer any.
2 years ago at 6:50 PM
DON'T ASK THE ATF QUESTIONS. PERIOD. We wouldn't begin a fraction of the mess we're in if so many supposedly \"gun\" folks didn't go to the trouble of asking ATF questions. If enough folks pester them then they feel obligated to render an \"opinion\". Not a law. They don't make the laws but their opinion sets a precedence which in effect becomes how the law is interpreted. So Leave. Them. Alone. If you don't know enough to not put a vertical grip on a pistol of any kind perhaps you don't need to own a pistol. Harsh? Nope, logical. With idiot cowards doing what they are doing and the media making rockstars out of them and politicians standing in the blood of victims to preach for disarming us all we will be lucky this side of another revolution to be able to keep ANY firearms. Unfortunately the gun/freedom haters know all this and probably account for a lot of stupid questions to ATF and may be willing to sacrifice even more to disarm us. PSA shelves should be emptying fast with orders because change, bad change is coming soon. These are the \"good old days\" we will look back on. Buy while you can at current PSA prices.
2 years ago at 6:50 PM
You are 100% correct. I hear I will never give up my guns, Or you can have them Bullets first. In a different mix of people I hear from the same people, I have a family to care for a job I have to go to. So did our founding fathers. Most lost everything for America. Most of the talkers will do nothing to stop the takeover of our Government by the Democrat/Socialist What is your freedom worth ? If you don't believe that the Democrat/Socialist are doing their best to shove socialism down your throat ask anyone from one of the Communist countries that has fled here and become an American. They will tell you what you are giving up with out a fight. If you like your freedom to own firearms assemble as you chose and choose what you read and watch don't be sheep. Make noise look what a small part of our population did in the 60's. Stop sending your children to the so called institutions of higher learning that are just brainwashing them. Cut off the MONEY. I can't understand why you keep sending your children to the Socialist professors to brainwash our future.
2 years ago at 9:42 PM
Thinking about the other end of the gun, if I use an 11\" barrel inside of a 12\" rail, do they measure to the end of the rail since it is an integral part of the gun, or do they take my muzzle device off and measure to the end of the barrel? Traditionally the barrel would extend beyond the rail and that is what they would measure.
2 years ago at 6:13 PM
I would recommend referencing the ATF's website when measuring for AOL's. Here is a link to their website.
Sam T
1 year ago at 9:22 AM
Confusing to say the least. Let's say someone's AR has a law tactical adapter and a collapsible brace. 1- Should the OAL (overall length) be measured with the law tactical folder in the folded position? PS. The AR can still shoot 1 round with the law tactical folder in the folded position, so for me it could be considered fully functional, but I don't know for the ATF. 2- If the OAL has to be measured with the Law Tactical adapter unfolded, should I subtract the size of the adapter from the OAL? 3- Do any of the 1st and 2nd questions apply to the LOP (length of pull) measurement?
1 year ago at 9:22 AM
I would point out that the law 3 is not designed to be fired while in a folded position. It also says specifically on it to "close before firing". It is designed for the weapon to operate under normal conditions in the closed position. It also should count as part of the OAL measurement because its not able to be removed from the weapon without causing it to remain functional. If you took it off it would be major disassembly of the firearm and it would not be able to fire without it. Thats why the measurement doesn't count for the collapsible brace or a muzzle break unless the brake is pinned or welded.
1 year ago at 10:24 AM
trying to figure this out myself, this does appear to be the arguable part of it, firing configuration. and i reckon it would be TBD based on LEO objectivity. Rifle rules are pretty specific, "pistol" rules not so much
1 year ago at 10:55 AM
How should I measure the OAL when I have an adjustable brace? Is it with the brace fully extended to the end of the barrel or fully collapsed? And if I have a compensator is that included in the measurement?
10 months ago at 10:40 PM
Maybe I'm splitting hairs here, but are they refering to a brace attached by a folding mechanism like a Sig MCX where there is no buffer tube needed to function? It kinda reads that an AR pistol with a 10.3" barrel's OAL would be measured with the folding mechanism open as that's needed for the firearm to function, although technically it could still fire one round folded.....
10 months ago at 11:17 AM
I would recommend reaching out to your local ATF branch for their interpretation. My understanding is that if it could fire with the brace folded, you would measure with it folded. You do not get to include the brace in the measurement.
4 months ago at 11:59 AM
this discussion is about the buffer tube being included in the oal of a ar but not in the folded position I guess. What if I build a sa pps43 and somehow put a folding buffer tube and stabilizing brace on it, I'm thinking by what I read it will be a pistol still but wiyh a arm brace added but foldable for storing or shooting as with a arm brace? correct?