I have a Savage 340C(carbine) in 30-30 Win that is all original. Im having problems with some of the cases sticking in the chamber after its fired. I open and go to pull the bolt back and it wont pull the fired case from chamber. The shell extractor seems to be in ok shape and I also inspected the chamber and it seems fine with no erosion. Their getting stuck enough to where I have to knock it out with a cleaning rod. Its not happening on every round but enough to concern me that I put it away till its fixed. The cartridges used are Winchester and Hornady factory ammo and not reloads. Any ideas of whats wrong???