Barrels are consumables. You are wasting time and money dicking with a shot out barrel.
Now if you chamber your own stuff, you can do a chop/setback and get some more life out of it, but not worth paying someone to re chamber it (hence why if you do your own work, it can be worth it).
Groups will open up, velocity will drop, will start throwing flyers, SD will grow.
When in doubt, throw it away. If you shoot a moderate amount you should always have a fresh barrel or two waiting to spin on when the last one gives up the ghost or is pulled a precautionary round count.