That's it - keep pestering ATF like you did when you were a kid (to your parents) - they will reverse it and make things worse for all.
“if this device, un-modified or modified; is assembled to a pistol and used as a shoulder stock, thus designing or redesigning or making or remaking of a weapon design to be fired from the shoulder; this assembly would constitute the making of a “rifle” as defined in 18 U.S.C. Section 921(a)(7).”
Read more here:
http://blog.princelaw.com/2014/12/2...ry-tale-of-an-ar-pistol-to-sbr-through-magic/
EXCERPT:
FTISB correctly finds that the SIG Brace is NOT designed or intended for firing a weapon from the shoulder. In its original determination letter, the Firearms Technology Branch (FTB) found that the brace when attached to a firearm did not convert it to be fired from the shoulder and would not alter the classification of the firearm.
FTISB says the same thing in the beginning of this new determination but goes on to say that if it is USED as a shoulder stock the classification changes. We are left to extrapolate that FTISB arrives at this conclusion because the user must have designed or redesigned or made or remade the firearm to be fired from the shoulder. Of course, they are careful to not acknowledge where that act actually occurs which poses all kinds of issues.
But did the end user actually design or redesign or make or remake the firearm by shouldering a firearm equipped with the SIG Brace? I think not. NFA defines the term “make” for us.
“Make.—The term “make”, and the various derivatives of such word, shall include manufacturing (other than by one qualified to engage in such a business under this chapter), putting together, altering, any combination of these, or otherwise producing a firearm.” 26 U.S.C. § 5845(i)