Sig Brace illegal to shoulder

[MrDraco]

NO.

" The pistol stabilizing brace was neither “designed” nor approved to be used as a shoulder stock, and therefore use as a shoulder stock constitutes a “redesign” of the device because a possessor has changed the very function of the item. Any individual letters stating otherwise are contrary to the plain language of the NFA, misapply Federal law, and are hereby revoked."

And by using this same logic, if you shoot a rifle one handed (as I've seen other people do with smaller calibers) I have thus "redesigned" the gun and legally made it into pistol. In order to redesign something, you have to physically alter it so it is made to perform differently, not simply use the item in a way the manufacture didn't intend. A wrench used as a hammer does not immediately become a hammer, it is still a wrench.