3rd build, have read all Sweeny’s and Own all Zediker’s books on ARs and know enough to run up the barrel but and back off a few times to help seat the final attempt to achieve the required torque.
This build was just adding a 15" key mod railed forend ($55 from Delta Team Tactical) in place of the free-floated carbine forend, but the nut would not budge once ‘tight’. I ended up ‘dressing’ the ends of the threads, just removing any color with a few strokes of a diamond stone.
But there was NO WAY otherwise that I would have seated it to the next gas tube alignment hole above the minimum required torque otherwise.
What says the more experienced builders? What tips do others have to offer?