I have a new 700 300WM that I have been breaking in and trying different loads with. So far, I can't get groups worth crap. I noticed after I removed cases that had just been shot from full-length sized brass the first time that it would eject the cases without much resistance, but it was putting about an inch long pretty deep scratch towards the neck end of the case bodies with each case. Last night while looking into the chamber the best I could with a flashlight to see if I could see any machine markings left by the factory reamer, I could not notice any. I thought I would try and rechamber the once-fired brass, that had been full-length sized and trimmed before firing the first time, and see if it would scratch them any worse. Some cases would allow bolt closure to chamber the case and others would not. I would have to take a small plastic mallet and knock the bolt back and enter a cleaning rod through the muzzle to knock the case out of the chamber on the ones that the bolt would not close on. Do you think there may have been reamer chatter to the chamber from the factory making the chamber oblong since some cases will rechamber and other won't? I mean all the cases were fireformed to only this rifle's chamber, the should all rechamber right back......correct?