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Primers not seating evenly.

Greetings all. Like most reloaders, I lean toward the perfectionist side of the equation. My 550B is a jewel, and I pride myself on turning out lots of near-perfect ammo each month. I do have a small issue that bugs me more as the rest of my process nears perfection: my primers do not seat evenly in the pocket. When I mic them, one side is invariably flush with the head, the other side deeper - near or on the desired primer depth. This is with pockets that are new, dirty, swaged or unswaged alike, and in all calibers with all primer makes. I've tried exerting more force on the seating stroke, rotating the shell plate to other positions, but no joy. (Thanks for any suggestions - including don't pet the sweaty things Mike.)

There are a few potential causes. The most likely is the shellplate bolt needs to be slightly tighter. Push down on the edge of the shellplate between stages 2 and 3. If it feels springy, then the shellplate bolt can be set tighter, a 1/32nd to 1/16th of a turn will probably suffice.
Next, when you push the handle forward, be sure the handle does not stop against the loaded cartridge chute. If necessary, reposition this chute to prevent this.
Finally, inspect your crank for hairline cracks. Since your primers seat, just not evenly, it is most likely that the shellplate bolt needs to be slightly tighter

Thanks for the feedback. I did as you suggest and yes, an improvement! The shell plate now has very little play, and everything feels a little more squared away.

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