I am not trying to minimize your plight here at all, and maybe pics with descriptions may help, but realize, almost all bore scope owners are self taught.a Lyman's bore scope pics? Is there a post on bore scope pictures showing what u are looking at? how to ID the different spots of build ups?
In my experience, those are the barrels that die early/sooner.I'm one if those that don't expect a used barrel to be "new clean" kinda like a used shovel, knock the chunks off, keep it from rusting !