Re: Stuck rounds in .308 Semi Auto
If I'm following correctly, the brass was fired in another gun, and then resized and fired in the DPMS? If so, then that's likely the problem, and the Small Base Dies Bob recommended should cure the sticking. You might want to use these as your standard dies for this rifles anyway from this point on. Many folks aren't aware of this, but full length sizing in most makes of dies do not return brass to its original, unfired dimensions. Small Base Dies are simply of somewhat tighter dimensions than regular full length dies, and will bring brass back to nearly its original unfired measurments. I'd suggest starting with new brass for this combination, and using the Small Base Dies from this point forward. Most makers offer these types of dies, so just double check that that's what you're getting when you order. Another item that I'd very strongly recommend is a chamber gage or other type of headspace gage so that you can measure just how much you're bumping the shoulder when you set up your dies.
Reloading for semi-autos is a bit different from what you might be used to with a bolt guns, and it needs to be approached from a very different perspective. Forget anything you know about benchrest reloading, and a good bit of what you know about reloading for bolt guns in general.
Hope this helps,