A while back I picked up a rem 700 7mm rem mag, used. I just recently took it out to shoot for the first time. I'm not a hunter and only picked it up for a possible project down the road. The bolt is really stiff, and after I put about 10 rounds of standard velocity box ammo thrpugh it, the bolt wouldn't come back to eject the spent round. I could rotate it but it wouldn't travel back until I let it sit for about 10 minutes. It is an ADL in the black polymer stock. I'm not sure how old it is, though. Any ideas?