Real time inventory. No backorders. Ships within 3 - 5 Business Days!

Will Your AR Pistol Become an SBR? ATF's New Pistol Brace Rules Explained

Will Your AR Pistol Become an SBR? ATF's New Pistol Brace Rules Explained

Posted by on Aug 15th 2021

You've probably heard that the ATF is, yet again, flip-flopping on the legality of the AR-15 pistol brace. In 2014, the agency said pistol braces were fine. They flipped in January, 2015 and said that shouldering a brace meant your pistol was now suddenly an SBR. They flopped again in 2017, saying braces were fine. Then the ATF tried to ban the Honeybadger AR pistol, only to be met with a hurricane of dissent from the public and legislators. Now the ATF is topping off its stack of pancakes to ban the use of pistol braces for about 40 million gun owners, once and for all.

New Factoring Criteria for Pistol Braces

Pistol braces have a genuine use, especially for millions of injured servicemembers, veterans, and amputees: They allow disabled gun owners to enjoy America's most popular firearm, the AR-15. "We're not banning braces!" Says the ATF, knowing their agency and this proposal are despised. They're "only" restricting whether you can install one on your AR-15 pistol without making it an SBR, using a special points system.

So, what does this all mean? The agency released a document titled Factoring Criteria for Firearms With Attached 'Stabilizing Braces'. It's a monologue running dozens of pages that seeks to justify this de facto ban. It also spells out complex new guidelines that will determine whether your pistol, when equipped with a brace, gets redefined as a short-barreled rifle. Spoilers: It probably will be.

Redefining the word "Rifle"

The ATF first wants to redefine what a rifle is by adding the following language to the current definition:

"The new sentence would clarify that the term 'rifle' includes any weapon with a rifled barrel and equipped with an attached 'stabilizing brace' that has objective design features and characteristics that indicate that the firearm is designed to be fired from the shoulder, as indicated on ATF Worksheet 4999."

AR-type pistols are defined as firearms with no stock and a barrel shorter than 16". If the ATF gets to say that a pistol with a brace is now a rifle, they then get to call that pistol a short-barreled rifle, or SBR (an NFA firearm) since its barrel is under 16". Owning an SBR without special approval is illegal. The ATF's new Worksheet 4999 provides the points system they want to use to reclassify most pistols with braces as rifles.


Your pistol has to meet certain weight and length criteria before you can even see if it's eligible to remain a pistol with a brace by using the points worksheet. The ATF says if your pistol doesn't meet these below criteria for height and weight, it can't have a brace under any circumstances.

Weapon Weight

If your pistol is too light, they say it can't have a brace at all, because (this is what they actually claim), "Firearms weighing less than 64 ounces or 4 pounds are not considered weapons suitable for use with a stabilizing brace because they are more easily held and fired without the need for one."

We find it remarkable that the ATF is deciding how physically disabled a gun owner is allowed to be. We'd love to hear how they determined that using a brace on a lightweight firearm is somehow more difficult than not using one.

Overall Length

Your braced pistol must measure between 12" and 26" (with the brace fully extended, if adjustable) to remain eligible as a pistol using the points system. If your AR measures less than 12 inches or more than 26 inches, the agency claims that -- and they actually state this -- using a brace on such a firearm is impracticable because doing so would "cause an imbalance." 

Yes, stabilizing braces cause, uh, instability.

ATF Worksheet 4999

If your AR pistol meets the prerequisites of weighing at least 64 ounces and having an overall length of 12 to 26 inches, you get to play the ATF's new game called Worksheet 4999. The points your pistol earns are based on the firearm's characteristics and vary from 1 to 4 points per item. These are the excuse-- sorry, we mean criteria the ATF came up with to assign these points.

  • 1 point: Minor Indicator (the weapon could be fired from the shoulder).
  • 2 points: Moderate Indicator (the weapon may be designed and intended to be fired from the shoulder).
  • 3 points: Strong Indicator (the weapon is likely designed and intended to be fired from the shoulder).
  • 4 points: Decisive Indicator (the weapon is designed and intended to be fired from the shoulder).

If your pistol obtains 4 points in any of the worksheet's sections, then it'll be considered an SBR. Points are not added up from all sections. For example, if your pistol scores 3 points in section II and 3 points in section III, this does not equal 6 points. It remains 3 points.

SECTION I: Prerequisites

First, you need to confirm your AR meets the weight and length requirements. If it does, proceed to Section II. If it does not, you're likely to become a felon if you don't remove your brace.

SECTION II: Accessory Characteristics

  • Not based on a known shoulder stock design: 0 points
  • Incorporates shoulder stock design feature(s): 1 point
  • Based on a known shoulder stock design: 2 points.
  • Device incorporates features to prevent use as a shouldering device: 0 points
  • Minimized Rear Surface lacking features to discourage shouldering: 1 point
  • Rear Surface useful for shouldering the firearm: 2 points
  • Material added to increase Rear Surface for shouldering: 3 points
  • Non-adjustable, fixed design: 0 points
  • Adjustable or telescoping attachment designed for shouldering: 2 points
  • Counterbalance Design - Non-Folding: 0 points
  • Counterbalance Design that Folds creating Rear Contact Surface: 1 point


  • "Fin-type" design WITH Arm Strap: 0 points
  • "Fin-type" design WITHOUT Arm Strap: 2 points


  • "Cuff-type" design that FULLY wraps around arm: 0 points
  • "Cuff-type" design that PARTIALLY wraps around arm: 1 point
  • "Cuff-type" design that FAILS to wrap around arm: 2 points
  • "Split-stock" configuration not designed to wrap around shooter's arm: 3 points

Here, you're supposed to tally up how many points your braced pistol has earned. Then proceed to Section III.

SECTION III: Configuration of Weapon

LENGTH OF PULL - w/ Accessory in Rear most "Locked Position"
  • Less than 10-1/2 inches: 0 points
  • 10-1/2 but under 11-1/2 inches: 1 point
  • 11-1/2 but under 12-1/2 inches: 2 points
  • 12-1/2 but under 13-1/2 inches: 3 points
  • 13-1/3 inches and Over: 4 points
  • Standard AR-type Pistol Buffer Tube (6-6-1/2 Inches): 0 points
  • AR-type Pistol Buffer Tube with Adjustment Notches (KAK-type): 1 point
  • Adjustable Rifle Buffer Tube: 1 point
  • Adjustable PDW-type guide rails: 1 point
  • Extended AR-type Pistol Buffer Tube: 2 points
  • Inclusion of Folding Adapter extending length of pull: 2 points
  • Use of “Spacers” to extend length of pull: 2 points
  • Modified shoulder stock with rear replaced by “stabilizing brace”: 3 points
  • Attachment method creates an unusable aim-point (slant): 3 points
  • “Cuff-type” or “fin-type” design with strap too short to function: 2 points
  • “Cuff-type” or “fin-type” design with strap made out of elastic material: 2 points
  • “Fin-type” lacking an arm strap: 2 points
  • “Cuff-type” design with strap REMOVED: 4 points
  • “Brace” accessory modified for shouldering: 4 points
  • Modified Shoulder Stock (originally a Shoulder Stock): 4 points
  • Presence of a Hand Stop: 2 points
  • Presence of a Secondary Grip (indicating two-handed fire): 4 points
  • Presence of Rifle-type Back-up / Flip-up Sights / Or no sights: 1 point
  • Presence of Reflex Sight with FTS Magnifier w/ Limited Eye-Relief: 2 points
  • Presence of a Sight/Scope with Eye Relief Incompatible with one-handed fire: 4 points
  • Presence of a bipod / monopod: 2 points
  • Weapon as configured weighing more than 120 ounces (magazine unloaded): 4 points

Here, you must tally up the points your braced pistol accrued in only Section III. Don't add Section II's points to your total. If your pistol scores 4 points or more in either section, the ATF claims your pistol has a "shoulder-fired design" and will be considered a short-barreled rifle.

Actual footage of ATF agents calculating the magical points so virtually all braces are banned.


Q: These rules sound dangerously vague. How can I know what points I earn?

A: You can't be certain. Such vague language like "Rear Surface useful for shouldering the firearm" and "Material added to increase Rear Surface for shouldering" is unheard of in real laws that are properly written by actual legislators. Even one of the ATF's own former agents says this is doomed to fail if it is passed.

Q: What's the point of all this?

A: There is no point. At all. Pun intended.

The ATF claims that restricting pistol braces will stop criminals from using them. They know this is not true, as any reasonable person knows. Braces will still be readily available, just like any other firearm accessory. There's nothing here that will stop a criminal from slapping a brace (or even a stock) on any firearm and using it in a crime. Why would criminals care about violating some ATF policy? They don't. This proposal only affects law-abiding citizens, especially injured veterans and disabled gun owners. And it does so needlessly.

Q: What can I do if this proposal becomes law?

A: If your pistol gets reclassified as an SBR, the ATF says you can 1.) Destroy your pistol brace, 2.) Install a barrel longer than 16", 3.) Destroy your firearm, 4.) Turn the firearm into your local ATF office, or 5.) Apply for a Form 1 tax stamp under the National Firearms Act to legally build and own an SBR.

Q: How do I apply to convert my pistol into a legal SBR?

A: We wrote up a very detailed, step-by-step guide that walks you through the process. The application can be completed online and approvals typically take a few weeks. Once approved, you can keep your brace or install a buttstock.

Q: What can I do to stop this?

A: You can comment on this proposal through the Federal Register. The ATF is required to read and respond to public comments before proceeding with any rule-making. The comment period is open until September 8th, 2021 at 11:59PM Eastern time. You can also write the agency by mail. Submit written comments to: 

Denise Brown, 

Mail Stop 6N-518,

Office of Regulatory Affairs, Enforcement Programs and Services, 

Bureau of Alcohol, Tobacco, Firearms, and Explosives, 

99 New York Ave. NE, Washington, DC 20226

ATTN: ATF 2021R-08

DISCLAIMER: If you are new to the world of DIY gun building, you likely have a lot of questions and rightfully so. It’s an area that has a lot of questions that, without the correct answers, could have some serious implications. At, we are by no means providing this content on our website to serve as legal advice or legal counsel. We encourage each and every builder to perform their own research around their respective State laws as well as educating themselves on the Federal laws. When performing your own research, please be sure that you are getting your information from a reliable source.

We are a national retailer of individual components and not all products depicted on this website are legal in every state. Shipping of various products found on this website are prohibited to some states (such as California, Connecticut, District of Columbia, Hawaii, New Jersey, New York, Rhode Island, and Washington). The information, pictures, text or products presented on this website are not a representation by us, and should not be understood by you, that any product or completed firearm is legal to assemble or own in your state of residence. We encourage each and every builder to perform their own research about the state and federal laws that apply to them. It is your responsibility to understand the law and we encourage you to consult with an attorney or your local ATF representative.