Yup the dreaded red liner
Been thre done this. Her's my experience. I burned it out 3 times. Went after it with 4 wire wheels and then hand sanded for about 2 hours. If I was to do it again, I would pay somebody to sandblast it. If memory serves it was about $35. Once you add up your time, wheels and sand paper your're gonna wish you blasted it. Just my $.02. Or look for an unlined barrel.