Barrel threading is one of the most important steps in getting the most out of your suppressor purchase. If the barrel is not threaded properly you can experience a range of issues from excessive P.O.I. to damage to your suppressor or rifle. To get the best from your suppressor your barrel has to be threaded through the headstock using a range rod and two indicators AT THE MUZZLE. Do not indicate in on the spider side, only use the spider to get the range rod running dead true. If your gunsmith does not thread using this method do not trust them with your firearm, period.