I too have a new Trophy Hunter .308 and had this exact same problem the other day. I was shooting it for the first time the other day and was shooting Remington Core-lokts and Hornady Whitetails. The Core-lokts chambered very smooth, while the Hornadys were noticeably harder to get the bolt to close. I'm glad I found this thread and and confirmed my suspicion that it was just the ammo.