Disclaimer: I am not a lawyer; no one in this office is a lawyer. This information is based on current research. Laws get updated; this article, probably not. So, before you do anything involving SBRs, make sure you contact the local ATF Division about the laws in your state. 

There’s one clear difference between an AR-Pistol and a Short Barrel Rifle (SBR), and that’s the stock. Why that matters depends on your desire to commit a felony, although we’re thinking you’re not, and that might be why you’re reading this.

Maxim Defense MD 15 SBR
Photo Credit: Maxim Defense | MD:15 (Pistol Brace)


Photo Credit: Maxim Defense | MD:15 (SBR)

You see, you can put pistol braces on rifles all day long, and you don’t have to worry about the feds coming after you (at least not as of the publication of this article). However, as soon as you put a rifle stock on a pistol, you’ll be committing a felony.

So, there you have it, that’s it. The only difference (what separates the legalities) is what type of stock you’re using. Okay, so that’s the end of this article.

I’m kidding; let’s talk about the difference between a pistol brace and a rifle stock, that way, we can give you a bit more clarification on when you need and don’t need a tax stamp.

Pistol Braces vs. Rifle Stocks

Pistol Braces

This might seem ridiculous, but when ridiculous gun laws are made, there will be people smarter than those laws, or smart enough to get around them—however you choose to look at it. And that’s basically how the pistol brace came about.

Unfortunately, there’s a lot of confusion about what makes a pistol brace a pistol brace and not a rifle stock because they look pretty similar when you’re looking at a fully assembled firearm.

So, to make things a little simpler, a pistol brace has a hole in it and typically has a Velcro strap that’s intended to wrap around the arm.

Pistol Brace

Typically, that same hole will open up to look like an A-frame, which helps to balance the pistol on your forearm.

You see, a pistol brace doesn’t actually have to sit on your arm, it just has to work as a brace, meaning it can sit against your arm as well (shooter’s choice).

Also, while a pistol brace can technically be shouldered, doing so on its own does not turn your AR-pistol into a SBR (as of the publication of this article—this could change tomorrow, for all we know).

Is shouldering a pistol brace legal?

Yes, the short answer shouldering a pistol brace without a tax stamp is legal by federal standards. However, let’s get a little deeper into the legalities because who doesn’t like doing that?

Like we said (as of this publication), shouldering a pistol brace does not make it a SBR, which means you don’t have to purchase a tax stamp and register it with the NFA.

ATF Open Letters

Something to keep in mind, the ATF likes to write these things called open letters. Unfortunately, open letters aren’t legally binding, and the chances of you using these letters in a court case—even though they came from the ATF—aren’t guaranteed. *Your chances improve if the letter is addressed specifically to you, but we aren’t lawyers, so maybe don’t take our word for it.

Even still, and you can take all that as you wish, the ATF made a statement in one of these letters saying that using a pistol brace from a shoulder-fired position, on its own, does not make it an NFA firearm.

NFA firearms require a tax stamp. If you’re purchasing an NFA firearm for the government or in an LE capacity, acquiring an NFA firearm looks slightly different.

However, according to the ATF, if you were to undermine the brace’s ability to be a brace, and made ”affirmative steps” in configuring the brace to work as a shoulder-stock, and ALSO shot it from the shoulder, then you have “redesigned” the firearm in a way that is categorized as a registerable weapon with the NFA.

What makes a pistol brace illegal?

Re-configuring your pistol brace to be a shoulder stock could get you in a little bit of hot water.

What does re-configuring a pistol brace look like, according to the ATF’s open letter? Glad you asked.

Examples, as given by the ATF:

  • Permanently affixing the brace to the buffer tube so that its length serves no other purpose but to be fired from the shoulder as a rifle stock.
  • Removing the arm-strap (Undermining the brace’s ability to act as a brace)

Again, you must do things like this and ALSO shoot it from the shoulder-fired position. These are also just examples from an open letter and have not become legally binding—as a reminder, this could change after we get this article published.

Why aren’t pistol braces considered rifle stocks?

So, what makes a pistol brace not a rifle stock since they can technically serve the same purpose?

Well, according to the ATF, it has not been re-configured for shoulder-fire, even if that’s how you use it. Why? Because apparently, it’s not intended to be shot that way, and it’s also not comfortable (subjective).

So, if you don’t reconfigure the thing, you are good—according to an open letter published by the ATF that is not legally binding but could change at any given moment. With that, I’d like to take a moment to tell you, stay up to date on federal and state gun laws so you don’t find yourself in a bind with the feds.

Rifle Stocks

Now that we’ve covered what makes a pistol brace a pistol brace let’s look at what makes a rifle stock a rifle stock. The short answer, it’s intended to be fired from the shoulder to absorb the recoil.


Maxim Defense SBR MDX 510
Photo Credit: Maxim Defense | MDX: 510 (SBR/Rifle Stock)

Yes, you can technically fire just about any weapon with one hand—safely, comfortably, accurately…that’s a different story, and it’s not how the gun gods determine the difference between tax stamp worthy and non-tax stamp worthy.

As soon as you place a rifle stock on anything that has a barrel length less than 16-in., then you’ve created yourself a SBR, and you better had received your tax stamp before you did it, or you’re committing a federal crime.

If you’re looking for more details, here are the most up-to-date pieces of information on SBR laws by state, as published by the ATF.

For more general definitions, as it pertains to the NFA, you should read the classifications of firearms.

The big difference, rifle stocks were not intended to act as a brace that sits on or against your forearm. They’re intended for shoulder-fired use, and when you start shortening your barrel so that it falls outside of the “rifle” definition, you are, in turn creating a SBR.

Recap: AR-Pistol vs. SBR

If you own a brace, it can function as a stock, so long as you haven’t re-configured it to serve no other purpose but to be a stock (ATF Open Letter). If what you’re using is a pistol brace intended to either fit around OR against your forearm, then it is legal without a tax stamp, and you have created yourself an AR-pistol.

If you place a rifle stock on a pistol OR you re-configure your pistol brace to act only for the purpose of being a shoulder-stock, then you have yourself a SBR, if the barrel is under 16-in., and you must purchase a tax stamp prior.

Basically, and for a purpose none other than simplicity, it comes down to intended use when your barrel is less than 16-in. Is it intended to be used as a pistol brace? No tax stamp is needed. Was it intended to be used as a rifle stock? You’ll need a tax stamp.

Disclaimer: Again, I am not a lawyer; no one in this office is a lawyer. This information is based on current research. Laws get updated; this article, probably not. So, before you do anything involving SBRs, make sure you contact the local ATF Division about the laws in your state. 

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