AR-15 Pistol Braces Explained [Free Online Brace Calculator] : Gun University

If you’re wondering what a pistol brace is, why they’re so popular, and whether they are legal, you’re in luck – we’re going to cover everything you need to know about pistol braces (sometimes called “pistol stabilizing braces”) in this article.

We’re also including a really cool calculator that will help you determine whether your pistol brace passes ATF’s new scorecard test.

What is a Pistol Brace?

A is sold as a device that is added to the rear of a pistol in order to give support against the shooter’s firing arm. Because a pistol brace is not technically a rifle buttstock (the part of a rifle that supports the rifle against the shooter’s shoulder), it is a bit of a legal loophole that allows a firearm to have a shorter barrel than it would be otherwise legal to have.

Let me explain.

The federal definition of a rifle (18 USC 921(a)(7)) is a firearm that is designed and intended to be fired from the should and which has a rifled barrel.  Therefore, if a firearm has a buttstock and the barrel contains the twisting grooves that impart spin on a bullet for stabilization (rifling), then that firearm is legally a rifle.

Another federal law (26 USC 5845(a)(3)) requires that rifles must have barrels at least 16 inches long and an overall length at least 26 inches long. If the barrel of a rifle is shorter than 16 inches, it is considered a “Short Barreled Rifle” (SBR) and it is subject to much stricter regulations and controls under the National Firearms Act (NFA) which include a $200 tax, ATF approval (many many months of waiting) prior to transfer, special engraving/marking requirements, and permission to cross state lines.

On an AR-15 style firearm, or “AR,” for example, the AR pistol brace is not different than any of the other AR parts (it is not a firearm by itself) other than it is the part that when attached to the buffer tube (the tube that sticks out the back of an AR-15 and which holds the buffer), it makes the firearm legally an AR pistol.

Pistol braces are not just for AR-15s – in fact, there are many firearms for which an arm brace can be purchased. For example, a conversion kit can be purchased to add a pistol brace to a CZ Scorpion EVO (instead of a shoulder stock).

If you’re already interested in getting yourself a pistol brace before they may be banned, we’ve compiled the best pistol braces for you.

Why are pistol stabilizing braces so popular?

Pistol braces are commonly known as a bit of a workaround to allow a firearm, such as an AR-15, to have a short barrel without needing to register the firearm as a “Short Barreled Rifle” (an NFA firearm).

Without using a pistol brace, if you wanted to install a barrel shorter than 16 inches on your AR-15 rifle, you needed to go through the NFA registration process. This process requires filling out an ATF Form 1, submitting it along with fingerprints, photos, and a check for $200 to the ATF, engraving your name and city/state on the firearm, waiting almost a year for approval fro the ATF before you could even have the parts in the same house, and then once you paid your tax and had permission to possess and install the shorter barrel, you were then subject to many other rules about where the firearm could be taken/used.

That was a pain the ass (by design).

If you used a pistol stabilizing brace, however, you could simply take off the rifle’s buttstock, remove some of the lower parts if you took off the buffer tube for your particular AR pistol brace, and then install your pistol brace tube kit onto the lower receiver. After you’ve done this, the firearm is no longer a rifle so your short barrel can be installed without any extra work, money, or legal hassle.

If you had a firearm like an Sig Sauer MCX, you could just remove the buttstock from the rear picatinny rail and install the pistol brace as one complete assembly. However, other similar platforms like the Sig MCX Copperhead already have a pistol brace from the factory.

AR-15 Pistol Brace Background

The ATF has had an issue with pistol braces ever since they came out and has tried various way to restrict or regulate their use.

SB Tactical was the pioneer of the pistol brace. They made the item with the advertised intent to help disable shooters handle AR-15 pistols. The ATF had no choice but to “approve” the items as they weren’t “designed and intended” to be fired from the shoulder.

Pistol braces became very popular and MANY Americans started making firearms into an AR 15 pistol instead of AR 15 Short Barreled Rifle. And, even though the items with technically a pistol stabilizing brace, they were used effectively as buttstocks when firing the guns.

The ATF’s first attempt to stop pistol braces was to claim that anyone who “shouldered” (meaning placed the pistol brace into their should for support when firing) a pistol brace has effectively “redesigned” the item into a buttstock and therefore had an illegal short barrel rifle.

Using a brace on a pistol in your shoulder did not “redesign” the item. This was absurd. I personally argued with the ATF over this news at a SHOT Show meeting with them and I made the argument: “If I took a bolt action rifle, like a Remington 700 for example, and fired it with the buttstock against my forehead, have I now redesigned it into no longer being a rifle since I didn’t use my shoulder?” 

Thankfully, the ATF finally saw the absurdity of their argument and backed off this stance. But, for a time, gun owners where prevented from “shouldering” a pistol brace.

Now, the ATF is back again trying to stop pistol braces…

ATF’s Latest Rule on Pistol Braces

ATF’s latest attempt to ban pistol braces includes a scorecard system.

This scorecard is largely due to the fact that the ATF has struggled to define what is a buttock or a pistol brace for a decade now.

Effectively, instead of outright banning pistol braces, which they have no authority to do yet that didn’t stop the DOJ from outright banning bump-stocks, they have compiled a list of features that can be evaluated to determine if the item in question is a brace or whether it is a buttstock.

The implications of this rule are HUGE. If the scorecard shows that your item is a buttstock, even though you bought it as a brace (and it was previously approved as a brace by the ATF), you would be a FELON if you possessed it with a barrel shorter than 16 inches and haven’t registered it as a Short Barrel Rifle (SBR).

As a note, being a felon would make you a prohibited person which means you could never lawfully posses firearms nor ammunition again.

The rule has not yet been published in the Federal Register (the first step to the rule making process) however it is expected to be published any day now.

ATF Pistol Brace Scorecard

The ATF scorecard for pistol braces from the Biden Administration is absurd. 

The amount of inconsistencies and ambiguities could easily take up their own article.

For example, if a score of 4 or higher is obtained from the scoresheet, the item in question would make the firearm a Short Barrel Rifle instead of a handgun with a pistol brace.

On the very first section, Accessory Design, your item can earn from 0 points (good) to 2 points (bad) based on unclear and arbitrary criteria.

If your item is not based on a known shoulder stock design, it earns 0 points. That might sound straight forward but what does “based on” mean? And “known” to whom?

If your item incorporates shoulder stock design features, it earns 1 point. Well, what is a design feature? If it’s black like a standard AR buttstock, is that a design feature? If it mounts onto a buffer tube, is that a design feature? Also, not “known” is missing.

If your item is based on a known shoulder stock design, it earns 2 points. It looks like “known” is back and we still don’t know to whom this must be “known.” 

It also invites more questions like: does the item incorporate some shoulder stock design features because it was based on a known design? If so, how many points does it get? Or, does it have some stock features but it wasn’t based on a known design, does it get 0 or 1 point?

Trust me, it gets WAY worse.

For example, in one section of the form, you get 2 points if your item is a “fin-type design without an arm strap.” However, later in another section, if your item is a “fin-type lacking an arm strap” it gets 2 points. Is this just an inept ATF with a redundant typo OR do you get four points total for the same fin-type brace without a strap?

And, if you add red dot sights with magnifiers that don’t have good eye relief for one handed shooting on top of the firearm, your pistol brace on the back of the firearm earns points. How does that make sense? 

Add iron sights? 1 point. 

Have no sights at all? 1 point. 

Have a bipod? 2 points. 

Hand stop present? 2 points.

Foregrip? 4 points.

As you can see, the proposed ATF Form is not exactly easy to fill out and calculate. That’s why we tried our best to give you an online calculator that breaks down many of these sections into yes/no questions and gives you a final score at the end. 

Pistol Brace Calculator

the GunUniversity online Pistol Brace Calculator leads you through a series of questions which will help you navigate through the proposed ATF scoring criteria.

This calculator will give you your score based on ATF Worksheet 4999.

If you need some help along the way, we’ve included some help below (you can click on the “learn more” links within the calculator as needed.

ATF Pistol Brace Scorecard Calculator