Have a new Ruger MKII bull barrel that is jamming with anything more than 5 rounds in the magazine. This is the 3rd MKII I've had, and the first to be any problem at all. The fired brass doesn't eject and gets stuck behind/above the newly fed round. Could this be from the new magazine spring force?? Just a question of breaking in that new mag? Any thoughts, or suggestions. I've tried different ammo, with no relief. Your help/suggestions would be appreciated. Thanks.