You can literally put anything against your shoulder, that doesn't make it a "stock".I can't imagine anyone not seeing this coming. When you have a "brace" that you put against your shoulder it becomes a stock and your pistol becomes a SBR. Play stupid games, win stupid prizes.
Putting a pistol AR against your shoulder makes it a rifle according to the ATF because a pistol doesnt use a shoulder brace. So yeah......to the ATF a wooden dowel would be a stock.You can literally put anything against your shoulder, that doesn't make it a "stock".