The gun groups well, patches are good and though I know little about metal fatigue, its had only moderate use in the three years since built.
Never any powder substitutes, Goex black only, mostly FFg.
Given the nastiness of the early patches, then subsequently cleaner ones and the fact it never did this before, I suppose it would not be liner.
Flannelett? That is certainly worth a try. Have never felt the barrel is as clean as should be given my efforts. Hopefully I can blame it partially on the patch material!
I do feel great relief that y'all are NOT telling me the barrel is toast and can only be salvaged by reaming. Though I wouldn't mind a .62