theddguide, that would be driving me insane. I personally would be taking it to a smith to get an opinion and he would hopefully take a look at the case and know what it would take to fix it.
All the best
Kevin
Just a thought, but it looks like you may have a burr on the edge of the chamber. You may or may not be able to get your little finger in far enough to feel without removing the scope. The lack of a mark near the shoulder seems to indicate that could be a possibility.............. Then again...