I found this interesting.

From a GunsAmerica post. link: https://www.gunsamerica.com/blog/atf...from-shoulder/)

There are two main takeaways to this ATF reversal on SB Tactical stabilizing braces. I want to put these right out front so there is zero confusion.
  1. This ATF reversal only applies to SB Tactical products. All other manufacturers of arm braces are NOT covered in this private letter. This cannot be overstated. The letter only applies to SB Tactical and SB Tactical products!
  2. The ATF did, indeed, reverse its position with respect to SB Tactical’s proprietary pistol stabilizing braces. Shooting them from the shoulder no longer counts as a “redesign” of the products which previously made them subject to National Firearms Act regulations, i.e. short-barreled rifle. You can now fire an SB Tactical stabilizing brace from the shoulder and NOT be in violation of the law!

Yes, those are the two main takeaways from this story. How did this come about?

Lawyers for SB Tactical received a private letter from the Bureau of Alcohol, Tobacco, Firearms and Explosives that reads, “Re: Reversal of ATF Open Letter on the Redesign of ‘Stabilizing Braces.’” In this letter (see below) the ATF carefully explains in a not-so-easy-to-read manner the nature of the agency’s reversal and how it applies to SB Tactical and SB Tactical only.

After first saying that ATF “stand by those conclusions” in its 2015 Open Letter, the one that caused so much heartache and confusion (ATF can’t admit it was wrong for liability reasons), the agency goes on to eventually state the following:
To the extent the January 2015 Open Letter implied or has been construed to hold that incidental, sporadic, or situational “use” of an arm-brace (in its original approved configuration) equipped firearm from a firing position at or near the shoulder was sufficient to constitute “redesign,” such interpretations are incorrect and not consistent with ATF’s interpretation of the statute or the manner in which it has been historically enforced.
In other words, it’s not a redesign of the firearm if one has a SB Tactical stabilizing brace and one shoots it from the shoulder.

But the ATF goes on to say that “an item that functions as a stock if attached to a handgun in a manner that serves the objective purpose of allowing the firearm to be fired from the shoulder may result in ‘making’ a short-barreled rifle, even if the attachment is not permanent. See, Revenue Ruling 61-45.”

Again, if you have an SB Tactical product, you’re technically okay if you incidentally, sporadically or situationally fire it from the shoulder. But if you put on a device that you intend to use clearly as a stock or if you’re in possession of a product that isn’t made by SB Tactical and you attach it to the gun and fire it from the shoulder, you may find yourself in hot water with the ATF.

“It has always been our belief that the addition of our Pistol Stabilizing Brace benefits shooters, both disabled and able-bodied, and that neither strapping it to your arm nor shouldering a brace equipped pistol would constitute ‘redesign’ of a pistol to a NFA firearm”, said Alex Bosco, inventor, founder and CEO of SB Tactical in a press release obtained by GunsAmerica.

“We are strongly encouraged by the ATF’s reversal of opinion and commend their willingness to continually review policy, including their own opinions, to ensure public safety and the fulfillment of their mission,” he added.

Why does this letter only cover SB Tactical products? The answer is because it is a private letter sent to attorneys representing SB Tactical and the letter relates exclusively to the company’s stabilizing braces that were submitted for ATF review. Hence the language in the one paragraph, “in its original approved configuration.” Moreover, there are additional points in the letter where similar products on the market are alluded to in order to underscore the exclusivity of the determination.

“If, however, the shooter/possessor takes affirmative steps to configure the device for use as a shoulder-stock — for example, configuring the brace so as to permanently affix it to the end of the buffer tube, (thereby creating a length that has no there purpose than to facilitate its use as a stock), removing the arm strap, or otherwise undermining its ability to be used as a brace — and then in fact shoots the firearm from the shoulder using the accessory as a shoulder stock, that person objectively “redesigned” the firearm for the purposes of the NFA.”

The key line is “removing the arm strap.” Can you think of another “brace” on the market that does not have a strap? That’s basically what the agency is referring to. That’s not to say that the manufacturers of other similar products won’t petition the ATF in the future to get a similar determination on their products. But for right now, it only pertains to SB Tactical.

Anyways, that’s the skinny on this letter. You may also be wondering why this and why now? Why did the ATF suddenly reverse its position? Well, let’s just say that there’s a difference between the culture of an Obama ATF and that of a Trump ATF. Along these lines, one can only hope that this is the beginning of more good things to come from a Trump-era ATF.