I got a phone call last night from an old friend who has a friend that is learning to reload. The friend had inherited his Dad's rifles and loading gear and decided to keep the tradition going. The problem he ran into was that on seating the bullet in the third of his prepped and charged cases, he was unable to remove the loaded round from the shell holder. After a long three way conversation is was determined that the primer had backed out of the case -evidenced by removal of the shell holder and actually viewing the primer. As it turns out, the brass he had was so old and work hardened that he (on advice of someone on a Forum) had removed the expander ball from the dies before sizing. This made for an overly tight neck. The real problem was that the brass -seemingly- had severely worn out primer pockets from some warmish loads his dad had favored. As near as I can tell, the seating of the bullet pneumatically pushed the primer out just enough to catch the shell holder. (He used a Lee Auto Prime and says the primers seated 'really easy, all the way') The shell holder was of an unknown make and didn't have that that set back relief groove in the face so I have know idea how far out the primer actually was.
I had him remove the seater die, replace the shellholder and cartridge. Run the ram up til the bullet was sticking out the top of the press where he could grab it with a pair of pliers while lowering the ram. He dumped the powder, reseated the primer using the RCBS primer seater on the press, and removed the case.
The usual advice to start anew with brass followed. I'm sorry he had problems but it was an interesting situation and one I don't remember encountering before. ~Muir
(That should read "Unusual", sorry. Not enough coffee)