I think the pill that folks are choking on here is not that the ATF can regulate SBR's (which, as much as folks may not agree that should be the case, is clearly within their authority), but rather, the ATF's redefinition of the term
re-design. The new meaning that they have assigned to that term just doesn't make sense to the average person. The commonly used term that meets the definition they want is
re-purpose, or maybe
use. That is:
If a part is used or re-purposed to allow a firearm to be fired in a manner inconsistent with the intent of its original or otherwise approved design, then (insert consequences here).
To my point, if you asked a large sample of persons to show you how to
use a screwdriver as a knife, many would pick it up and make a stabbing or cutting motion with it. But, if you asked folks to
re-design a screwdriver into a knife, the vast majority would likely conclude that sharpening it in some manner would meet that criterion. But, would
any of them simply pick it up,
use it to make a stabbing motion in the general direction of another person, and confidently proclaim that the screwdriver has now been
redesigned into a knife? I don't think so. Is that a perfect example? No. But I believe it provides some insight as to the common definition of the term
redesign.
In the above example, it could certainly be argued that the person making a stabbing gesture with a screwdriver had assaulted a passerby. But could it be argued that the victim was assaulted
with a knife? The penalty for an assault can certainly be increased because there is
also a law that allows such if the assault is perpetrated with a
deadly weapon, which carries a broad definition based on the possibility that an object may inflict death or great bodily harm when wielded by a person intending to do so. Further, such a law does not redefine what a screwdriver is. But, if the law only allowed increasing the punishment if the assault was perpetrated with a knife (and not a broadly defined deadly weapon), it would (in my view) be much more difficult, maybe even impossible, to convince a jury that any added charge for using the screwdriver during the assault was appropriate. (Surely someone on a jury would be a stickler for the language of the law.)
Like the screwdriver used above, and regardless of how the ATF is attempting to redefine the word, using a pistol brace inconsistent with its original design does not
redesign it (at least not by the common definition of the word). So, if the ATF wants to prohibit brace owners from shouldering their pistols (which - in my view - they clearly do), they should provide guidance which states exactly that -
and provide the appropriate references to the law that they are charged with regulating that allows them to prohibit such an act.
However (and I could certainly be wrong, but I'm using the
2014 ATF Federal Firearms Regulations Reference Guide as a reference) there is nothing in the LAW relevant to this discussion that allows the ATF to regulate HOW a firearm is used, only what design features are allowed or prohibited for different categories of firearms, and their transportation, sale, transfer, and possession.
Of course, in full disclosure, the above statements are my personal opinion. I am not a lawyer. Neither am I a judge or a jury. And, I'm certainly not volunteering to be a test case for this issue.