I am probably worrying for nothing but I took off the extractor, measured a live round and then put it in the chamber made sure the bolt would close, then added pieces of scotch tape to the end of the round measured them and then chambered them. Here is my data (the round was measured with calibers w/ hornandy's .308 bullet comparison attachment (Hornady Manufacturing Company :: Reloading :: Metallic Reloading :: Tools Gauges :: Lock-N-Load Gauges-Formerly Stoney Point :: Bullet Comparators :: Bullet Comparator Kits)

Round: 3.724
1st tape: 3.726 Chambered fine
2nd tape: 3.730 Bolt was tight
3rd tape: 3.735 Bolt would not close

I don't think this really proves anything...