I have a custom 300 WM with a Rem 700 action. Shot perfectly for 6 months. Then the problem started. With a cold barrel I can put 3 shots down range. On the fourth or fifth shot the case will not eject - the bolt comes back but the case remains stuck in the action. I am using factory ammo Nosler Accubond (tried other rounds and same deal..I have to push the case out with a cleaning rod to get it clear. I thought it might be the case but there are no marks on the brass at all. Before I take it to a gunsmith, has anyone had a problem like this before? How did you resolve it? Why would this happen after 3 or 4 rounds when the rifle warms up? I am inclined to think there is a problem with the action but there are still a few possibilities. Thanks for your advice.