I recently purchased an upper from another member with a 14.5" barrel. It has a pinned Surefire MB556K bringing it to 16"+ but the pin is not welded. The seller didn't advertise this as NFA. Said he got it new from Gun Gallery -which from what I've read do not pin muzzle devices. I've had other 14.5"ers and they were all pinned with spot welds making it a 'blind pin'. Seller insists it's GTG, I am not so sure. BTW I do have a SBR lower but my intentions were to use this on a non-SBR lower. Here is photo. Feedback would be appreciated. Thanks.