Hello, I have a friend that has an AR with a 14" barrel and he installed a 2" flash hider to the end. I tried to explain to him that the flash hider has to be welded or soldered to the end of the barrel or it doesn't count. He basically told me that I'm full of s&*t and that he has family in the ATF and he knows what's legal and what's not. I got on the ATF website but I'm having trouble finding ANY information on this subject. Can someone help out and point me to the right documentation to clarify this?