Builder, an adjustable reamer that adjusts from the end with a screw is welded to a 3/8 or 1/2 steel rod about three foot long with a tee handle on the other end. Another rod was drilled and slotted on the end so I could reach in and adjust the reamer while it's in the barrel. Years ago V.M. Starr wrote a little book about jug choking barrels and said it should be done 2 to 8" back, or for a 6" area. This allows the shot time to open up before it gets squeezed back down. The reamer is put in the proper place, and opened up a thousand or two. You're trying to open it while it's against the barrel. Then it's twisted and pulled back and forth for 6". Maybe tighten it once or twice, then loosen it and remove it to clean it from shavings. Do it all over till you get what you want. I usually wipe the barrel clean after a time or two and check it with a dial indicator. When done a barrel " ball hone " is used to smooth things up and finally some steel wool on a barrel brush. Hope this helps. Paul
