I was re-reading this thread. i don't see where you used anything stronger than xyz juice and patches....or Wipeout.
It is simple.
If you have fired a bunch of rounds down the tube, especialy a factory tube, you will have some carbon fouling. There is no cleaning jucie that cleans, removes, disolves, or does ANYTHING to carbon. Carbon needs to be physicly scrubbed out of the bore with either wet bronze brushes or IASSO/JBBore Paste. More often than not you will have copper under the carbon...or many layers of both.
Eventially, the carbon thing will catch up to you. Degridation of accuracy at best.....unexpained PSI trouble at worst.