Load data would help identify a problem. Light loads will let the primer back out. The head to datum shoulder set back from sizing, .020" seems excessive, when the bottom of the die is contacting the shell holder? Strange. Edit/add> From your other post-
The difference between new brass and f/f brass in my Savage 7mm Rem mag is .022" using the Hornady headspace comparator.
Common, as factory is most times underside. To get a true reading of the head to datum measurment of a fired case, neck size only till bolt closes hard. Or back the FL die out .010" and size, see if sized case will chamber. If not move the die down more. Near maximum loads are needed to full expand the brass.