I had the same problem with my MK II in 22 mag. I took some doing but I was able to fix it. First I ordered a second clip extractor and fitted it over the first one to increase the tension on the extractor. Second, I found a burr on the back edge of the chamber edge, I used a Q-tip to find it. I also cleaned the chamber and was able to stop the issue. Oddly enough only the Hornady V- ammo was causing the problem. But V-max is the most accurate in that rifle.
