[Full Length Re-size Die]
I had the same thing on my Rem 700, the bolt needed too much force to close and lock. There was a buildup of brass shavings behind the extractor, so the case wouldn't slide all the way into the bolt face. Mine had a fixed extractor, so that's why it occasionally does this. Another idea would be to look into chamber to see if there's a buildup in the neck area, I've seen that too, but only once.