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Are You Committing a Felony? New Rules, How to Measure a AR-15 Pistol

NFA 101

As of July 5th, 2019 rules regarding how pistols are classified in the United States have changed. Initially reported by the Prince Law Office, the ATF has issued a letter in response to a request on how to measure the overall length (OAL) of a pistol when equipped with a stabilizing brace.

The letter in question, dated June 25, 2019, is reported to have originated from a request submitted over a year prior. The original letter was a request about the correct way to measure a firearm equipped with a “stabilizing brace” or a folding adaptor. Below is an image of the full letter. But let’s break it down and discuss all the background behind this change and what it means.

ATF Definitions

The ATF defines a pistol as: “a weapon originally designed, made, and intended to fire a projectile (bullet) from one or more barrels when held in one hand.

The fact that the ATF defines a pistol as a weapon held it one hand is important because it distinguishes it from another category that is “any other weapon”. The ATF defines AOW’s as: “Any weapon or device capable of being concealed on the person from which a shot can be discharged through the energy of an explosive. Such term shall not include a pistol or a revolver having a rifled bore, or rifled bores, or weapons designed, made, or intended to be fired from the shoulder

According to the ATF, if you add a vertical grip to a pistol, then it is no longer intended for firing with one hand. In this case, the addition of a vertical grip makes the pistol an AOW. The same goes if you add a stock to a pistol then it is no longer a pistol and becomes a “short barrel rifle”. Which the ATF defines as: “a rifle having a barrel or barrels of less than 16 inches in length; a weapon made from a rifle if such weapon as modified has an overall length of less than 26 inches or a barrel or barrels of less than 16 inches in length;

A pistol stops being a pistol and becomes an NFA item and subject to a $200 tax stamp if you:

  • Add a vertical grip while your overall length is under 26″
  • Add a stock with a barrel under 16″

Stabilizing Braces

The stabilizing brace is available on a variety of firearms as a feature for people with mobility issues. The ATF has ruled that the intention of these devices was to help aid in firing pistols one-handed, not for taking the place of the stock. Adding a brace to a pistol can give you many of the same benefits of a stock. Without it actually being a stock and regulated under the NFA.

This is where the rule change listed above becomes important. In the letter the ATF states:

FTISB (Fireams Technology Industry Services Branch), 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 fireann 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.

A brace is not an essential element of a pistol since it is for stabilizing the pistol, not firing from the shoulder. Therefore in measuring the overall length of a pistol, you cannot include the length of the brace.


In reality, this new rule only affects people that want to add a vertical grip to their pistol. The reason that people would want to include the length of the brace is to make the firearm over 26″. This would make it not an AOW and subject to the NFA. The ATF recognizes this issue and included this section in the letter:

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.

Examples of firearms affected by the recent change are below. These are firearms that could have been over 26″ under the previous ATF ruling but are no longer. Without other modifications, the addition of a vertical front grip to these firearms would be illegal. 

CZ Scorpion EVO with Folding Brace
CZ Scorpion EVO with Folding Brace advertised as 29.4" with side folding stabilizing brace extended.
RUGER AR-556 PISTOL advertised as 27.90" with brace extended.
PSA PA-15 10.5” 5.56 Shockwave AR-15 Pistol
PSA PA-15 10.5” 5.56 Shockwave AR-15 Pistol over 26" with brace extended.
LWRCI SMG 45 advertised as 26" with side folding stabilizing brace extended.
Zenith Z-5RS SB Rail
Zenith Z-5RS SB Rail advertised as 26.6" with side folding stabilizing brace extended.

How to Measure Overall Length

If you want to add a vertical grip the ATF has stated this is the procedure to determine overall length:

  • Remove non-permanently attached muzzle devices
  • Extend of fold out the shoulder stock (not brace) to its extreme length
  • Close the action, if the firearm is the “break-open” type
  • Lay the firearm on its side on a table or desk. With the butt of the stock in line with the edge. Keeping the butt against one edge, bring the barrel of the weapon in line, and next to, a right-angle edge.
  • Mark the length of the true muzzle of the barrel. (not the end of the muzzle device)
  • The overall length of the firearm can be measured from the muzzle mark to the right angle corner nearest the butt for the stock. Or the extreme rearward point of the firearm.

For AR type firearms with a brace measure to the end of the buffer tube. For other firearms that have a folding brace then fold the brace and follow the steps listed above. In doubt as to the length of your firearm? Just don’t add a vertical grip and avoid any issues.

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