If headspace was excessive, then yes the ejector could be pushing the case forward enough to allow the primer to push out of the case when fired, which then having the case crammed back onto it... Check headspace with stock unfired rounds versus once fired rounds.. Also would be good to visually inspect the barrel and look for a possible carbon ring in the chamber/throat...that to could be jacking pressure, especially on factory ammo..got any pics of the cases/primers/ bolt face?