If you're going to have a re-crown this has got to be worth ago first. It's just a more aggressive approach than my pencil and abrasive steel polishing compound fix.
K
I have found the problem I hope. After thoroughly cleaning, I can see a nasty carbon ring in the chamber at the point where the rifling starts. Having read a great deal about it, I am trying to remove it which is easier said than done. It has obviously been heat/fire baked on over many many rounds prior to my ownership. I won't go over the various things I have tried to shift it with but none have worked, much to my surprise. I am picking up some JB bore compound tomorrow and will be attacking it with that just in the chamber. I will win eventually even if I have to throw the thing out the window and buy a new rifle.