Quote Originally Posted by Fenrir View Post
The other possibility is your cases are not being adequately resized and the back end of the fired cases are sticking in the chamber. Does the bolt produce a distinct “click” sound at the top of the bolt throw? You may need a collet resizing die like this one - http://www.larrywillis.com/ - to solve your problem. Again, a search will provide additional information.
I shoot several different belted magnums and have the die listed above. I have had the same problem with used brass not fired in my rifles, the collet die fixed my problems without issue. I'm going to be tied up for the next week, but if you want to send me your problem brass, I'll be glad to run it through the die for you and see if that fixes your issue. I bet it does.. Jim