I did not clean primer pockets until I started reloading black powder cartridges. I do not use a wet tumbling method so some times, there is significant carbon residue in the pocket which would keep a new primer from fully seating. To solve this problem, I cut the blade on a Yankee Screwdriver to fit the large primer pocket and gave the end of th tip a nice square edge. I made a wooden clamp that let me mount the screwdriver with the bit upward next to the turret loading press. Now, as I pick up a case to start the loading cycle, I observe the primer pocket and if carbon or media (I use walnut) is present in the pocket or flash hole, the case is placed with primer pocket over the screwdriver blade and given one or two downward strokes. Pocket is clean! I onlly do selected cases and have never observed any accuracy degredation with cases, black powder or smokeless, that are not given the screwdriver cleaner treatment.