Your very first thing to try is to clean the chamber very, very well, with a bronze brush (although I never use them the bore of any of my firearms, chemicals, patches & nylon brushes only). If extraction still proves to be a problem, then you can resort to using polishing compound (NOT rubbing compound). JB bore cleaner would work, as well as Mothers, Flitz and several others. I had a lot of trouble with my Ruger convertible Mag cylinder, until I polished up the chambers, now spent cartridges extract like they are supposed to.
Cheers,
crkckr