Hawkeye: did you have a scope mounted on that rifle when you took it to the range? If so, your problem with the empty cases being 'flipped' back into the gun may actually have been caused by the empty striking the scope adjustment knob and bouncing back into the ejection port. Actually, it never leaves the port - it is extracted and as the ejector impacts the case head and the case mouth moves out of the port - it is at that point that the case mouth impacts the scope adjustment know and the casse does not even leave the ejection port. That could be one cause - the fix is to rotate your scope 90 degrees - lots of lever guys have to do this.
If the bolt rides up and over the next cartridge in the magazine, two things may apply: and please don't take this one sideways as it has happened to me more than once - I didn't pull the bolt back far enough for the boltface to catch the rim and move the cartridge forward. If that isn't it, then it might be the magazine (if removable) or the follower/spring. You may need to check the magazine follower to see if it has a burr or a sharp edge on it that could benefit from an Arkansas stone or a Swiss file.
I had similar problems with a Rem 788 I once had and it was a pain in the ooogots to deal with. But, I finally got it to the point where she cloverleafed without problems - then I gave it to my brother. I fixed it. Mikey.