I had that problem with a 6mm BR I built on a Savage Model 12 action. There is a cam on the bolt handle which rides on a matching cam on the small piece which fits between the rear of the action and the bolt handle. When you open the bolt, that cam is supposed to pull the spent case out of the chamber so that you can slid it aft when you slide the bolt open. However, in my Savage (and apparently on many other Savages), the middle piece is too thin. That means the two cam ramps don't work against one another as designed, the case isn't broken free from the chamber, and it remains stuck when you try to move the bolt aft.

There are countless complaints about this problem on the Internet. Most folks say things like, "Take it to a gunsmith", or "Buy a better rifle". Eventually I found a discussion about not only the cause but the cure.

The answer is to disassemble the bolt and remove that intermediate piece. Get a couple of 6-32 set screws; some people call them "grub screws". Drill and tap the forward face of that spacer piece with the holes as close to 180 degrees apart as possible. Do some careful looking to make sure you're positioning the screws correctly. Install the screws and leave them proud of the surface by ten or twenty thousands of an inch. Adjust this distance as necessary during testing and then use locktite to hold them permanently.

The screws will act like an adjustable shim and will reduce the distance between the aft face of the intermediate piece (where the cam is) and the forward face of the bolt handle (where the other cam ramp is). Now, when you raise the bolt handle, the cams will interact and rather than force the previously too-thin piece forward without doing the intended job of primary extraction, your new set screws will bear on the aft face of the action, the cams will engage properly because you've removed the excessive slop, and the case will be broken free allowing you to open the bolt and extract the case as designed.

You might want to test your rifle by temporarily inserting some sort of shim, even a screwdriver blade, in the space between the intermediate piece and aft face of the action to see if the problem with your rifle is as I just described. If the case extracts when you decrease the space ahead of the intermediate piece, then think seriously about doing the modification. A Google search failed to turn up the pictures I found several months ago, but you might have better luck. Actually, if your problem is what I think it is, you can figure out what you need to do just by looking very carefully at how the cams work (or don't work) when you raise bolt handle. I hope my rather long explanation helps.