If Your Bolt Assembly Screw was loose, it’s good You got that tightened up.
Proud primers can can come from excessive Head Space, or thin primers bleeding back into the firing pin hole. I have had this situation bad enough with CCI 400 primers that a spent case would not go into the shell holder. My bolts are now Bushed with the firing pin turned to match. No more off center strikes, no more primer bleed, no more Fail to Fire with Small Rifle Primers.
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