The barrel wasn't bad; maybe five to ten degrees past where it should have stopped; so it didn't worry me much. I had read a post on the 24 Hour Campfire about how to tighten the threads up and always wanted to try it anyway.
The Campfire Post goes into plenty of detail so I won't here. (You have to scroll down a few posts to find the one on this topic). Really, all you do is take a flat-faced hammer and gently tap on the threads to tighten them up. You also do the same with the outside edge of the barrel shoulder where it meets the receiver. It sounds scary but it works.
The first order was to find a flat-faced hammer. Kind of like a blacksmith's flatter. The Campfire post says to get a small ball-peen hammer and grind the face flat. I went to the local Lowes looking for such a hammer and they didn't have a ball-peen hammer in any size. The only small hammer they had of any type was a carpet tack hammer. From a distance, it looked like it had a flat face but on closer examination it wasn't flat at all. One corner stuck out from the face like a cowlick.
I decided to look elsewhere and wound up a Tractor Supply. They had a smallish ball-peen hammer and it already had a flat face. It was cheaper than the defective tack hammer at Lowes too.
I rounded up Great-Grandfather's anvil and went to work tapping on the threads as I rotated the barrel. Progress came quicker than I expected and I was about half way through before I decided to film some of the process. The sound doesn't follow the picture at all. Its like watching an old Japanese movie with a bad dubbing job but it does show about how hard you tap on the threads. I shot it from the wrong side so you can't see the threads very much but you can still get the idea.
When I got done, the notch lined up perfectly with the barrel tightened down nice and snug.