Sig Sauer Challenges ATF Open Letter Regarding SB-15 Brace Use

According to the BATF, how one holds this may constitute a product redesign.

How to use or not to use, that is the question.
The Sig Sauer SB-15 stabilizing brace for AR-type pistols has exposed some sticky legal questions. Does the use of a product define its purpose? For example, if one uses a hammer to remove a corroded battery terminal from a 1970 Gremlin, does the use redefine that same hammer as a wrench?
Historically, the BATF, citing National Firearms Act (NFA) regulations, has adhered to clear boundaries related to the design of a firearm. If a firearm fell outside of technical definitions, its manufacture and transfer was deemed subject to the terms of the NFA. For example, if a manufacturer put forth a rifle with a 12-inch barrel, it would be subject to NFA restrictions. Clear enough, right?
In the case of the Sig Sauer SB-15 Stabilizing Brace, the ATF has gotten itself into a pickle. Initially, the agency issued a ruling in favor of the Sig Sauer stabilizing brace, stating that “We find that the device is not designed or intended to fire a weapon from the shoulder. Based on our evaluation, FTB finds that the submitted forearm brace, when attached to a firearm, does not convert the weapon to be fired from the shoulder and would not alter the classification of a pistol or other firearm.”
In a subsequent open letter, the ATF appears to contradict its stance of applying NFA regulations to firearms design rather than use. According to the newest ATF letter, “Because the NFA defines both rifle and shotgun to include any “weapon designed or redesigned, made or remade, and intended to be fired from the shoulder,” any person who redesigns a stabilizing brace for use as a shoulder stock makes a NFA firearm when attached to a pistol with a rifled barrel under 16 inches in length or a handgun with a smooth bore under 18 inches in length.”
In plain English, the ATF appears to have stated that the method of use of a firearm can qualify as a product “redesign.” Even though the parts and installation remain exactly the same, the method of holding a certain gun can create a “redesign” that makes it an illegal product. This opens up a can of worms that puts any barrel of monkeys to shame.  Back to the hammer example, if I strike a nail, the thing in my hand is still a hammer. If I smash it on a ream of copier paper, is it now a printing press subject to FCC regulation? Likewise, if one holds the Sig brace equipped pistol at shoulder height, is it illegal? What if the user mounts the brace an inch below, does that qualify as a redesign of the product?
Does a consumer’s use of a product define its intent? Does the ATF have the legal authority to define law? What is the legal authority of an “open letter” from a federal government agency? These questions and many more remain.
On January 21, 2015, Sig Sauer issued a statement addressing the issue:

“As reaffirmed in an Open Letter by ATF’s Firearms and Ammunition Technology Division dated January 16, 2015, the Pistol Stabilizing Brace (SB15 and SBX) is legal to own, legal to purchase, and legal to install on a pistol. SIG SAUER® believes that the PSB improves the single-handed shooting performance of buffer tube equipped pistols, and offers the product both as an accessory and pre-installed on a number of pistols.
“The Open Letter goes further to rescind a previous private letter regarding the ‘intent’ of the user of the pistol stabilizing brace. In the letter of January 16, 2015, ATF opines that a person’s actual use of the product as a shoulder stock can change the legal classification of the product. However, the Open Letter explicitly states: “ATF hereby confirms that if used as designed—to assist shooters in stabilizing a handgun while shooting with a single hand—the device is not considered a shoulder stock and therefore may be attached to a handgun without making a NFA firearm.”
“We question ATF’s reversal in position that the classification of the brace may be altered by its use. We are reviewing the legal precedents and justification for this position, and will address our concerns with ATF in the near future.
“We will vigorously defend the classification of all of our products and our consumers’ right to use them in accordance with the law. If we find that the open letter opinion is outside the scope of the law, we will seek further review.”

As the statement from Sig Sauer indicates, the company believes that how a customer chooses to use a product does not constitute a “product redesign.” Just because a consumer might use a can of creamed corn to pound a nail doesn’t make that packaged vegetable a hammer. It’s still a can of creamed corn, dented or not.
This is gonna get interesting folks.