So holding a pistol with two hands... "redesigns" the function, and it is no longer a one handed "pistol" you simply by the nature of using two hands to hold it, have "manufactured" an illegal weapon.
The BATF is being stupid about the way they're trying to straddle this issue, but it's not nearly as complicated as people want to make it.
If you put something on your pistol that looks and functions like a shoulder stock you MIGHT be able to get away with it if you have a really good cover story and can demonstrate that the device is actually intended to be something completely legal and that it functions properly as something other than a shoulder stock.
That's what SIG has managed to do. They've got a very good cover story and it's working for them.
BUT, if you then use that item as a shoulder stock, you've blown your cover story and you're in trouble because you've added an item to your handgun that looks like a shoulder stock, works like a shoulder stock and that you're using as a shoulder stock.
What if the brace was not there? Just the buffer tube... if you shoulder the buffer tube... (people do that)
The buffer tube isn't something that's been added to the pistol. It has to be there for the gun to function. Shouldering the buffer tube isn't any different, from a legal standpoint than shouldering the grip of a normal handgun--just a little less awkward.
Since their official stance on a handgun is any weapon designed to be fired with one hand... if you grip a handgun with two hands, you have changed that pistol into an AOW... Simply because you are holding it incorrectly according to their definition.
No, this is simply not true.
There's a HUGE difference between simply holding a handgun with two hands versus adding a part to the gun and then using that part as a shoulder stock.
Saying it over and over won't change anything. Anyone who isn't trying to be intentionally obtuse isn't going to be confused about the difference between adding a part and using that part improperly versus simply holding a handgun with two hands.