Good advice all around. My motto, (having worked on powder and pellet guns for years), is never rotate anythng in the bore. That's barrels 101. Second, if a rifle has a bad barrel, you need to determine if is slight ie burrs, light roughness, or if it needs replaced. Most barrelss, especially soft airgun barrels, if too rough, just need to be replaced. Not saying you can't improve them some, but bad is bad. IF you determine the fix is polishing, then I advise only using something like flitz or JB, and on a lead slug, but it can be done with tight patches if you get the hang of it.. I once had a 7mm0-08 Tikka, that just wouldn't group for sour apples. It would do 2-3" at 100 yards all day long. I decided to either fix or ruin it, so I started with a very tight felt slug and JB. After every 100 or so pulls thru, I would clean it and shoot it. After a while, probably something like 1000 passes, it would shoot 1" groups, and I stopped. I have also tried it on other guns and had the reverse effect, they shot worse, that's when it's time for a new barrel.
Barrel making and polishing is as much art as science. I'm sure barrel makers would say, it's all about tolerances, they're either there or they're not and if they're not, there's not a lot you can do.
off a gnat at 50 yards.
