I had an older AR that didn't like to eject spent shells. Drove me nuts for weeks. Finially in desperation I took an old cleaning rod with a chamber brsh attached and "chucked it up" in a drill motor and went at the chamber with lots of solvent and high speed. Problem solved. May be worth a shot (no pun intended).
BTW: Prior to the drill thing, the chamber "looked" fine...
We had an, I believe, Albanian SKS at the shop that wouldn't extract. It came in with a spent shell stuck in the chamber. It was well stuck!
After turning the air blue for a while I got it out. Chamber looked fine but I cleaned it anyway. It was filthy and the chamber was badly eroded (scored). The gun will never again shoot properly.
It turned into a parts gun.