case head swipes can be caused by lock time issues. If the bolt is trying to rotate while the case is still swollen to the chamber, with the amount of gas a carbine 308 produces, i have witnessed first hand that this can be the result. I too thought i had pressure issues on the factory ammo i was shooting. turned out not so much.
in my case an AGB was the fix paired with a heavier buffer. I was getting NASTY swipes and pressure signs and the gun was simply running way way way way overgasssed.
and that was before i even suppressed it :X
