I plan to build my first AR pistol (10.5" .300 BLK) and am wondering which brace to get. I've read aboout ATF rulings that say that shouldering with an unmodified brace does not "make" an NFA item, and I've also read that this pertains only to certain braces. I've also read that this is old news and that ATF has rescinded that ruling, making shouldering illegal. I'm not looking for speculation or opinion here, but am asking whether any member can speak definitively to the issue. TIA.