Just a tip from someone who has messed up lesser things no gun related by doing it one more time until there was not enough wood, metal, whatever. Stop if you are trying to keep it 19, not sure if you really have more space, you need 19 for what you are trying to accomplish and just hand it off to someone else who can do it on one more try.
Be it a lathe or whatever. Someone you have high confidence in, who has experience.