I had a .375 double in my shop that I think at one time had a stuck case in the right barrel. It seemed that the original onwer tried to get it out with a drill bet. The new owner of this rifle found out that a fired case only had a neck length of around .125" and a shoulder angle of about 35 degrees. I know how chambers can be sleved but did not want to try it since I have never done one.
After a phone call to David Trevelion, who recomened Ken Eversol I found the cure. He sleved the chamber and did a great repair. It was not cheep but well worth the price and the work was fantastic, you could not tell by eye that the gun had been worked on.