First time for everything I guess. After 14+ yrs and 1000s of rounds reloaded, I had my first primer detonate upon seating. Using RCBS hand primer with Federal 150s in .45 ACP case. Luckily I have always had the habit of angling the tool away from myself and trying to keep fingers clear of case mouth. Still my index finger is still tingling, ears ringing, and shorts have a bingo dauber spot in the seat.