Re: loaded ammo
It is generally not a good idea to tumble loaded ammo except for very short periods of time. It is believed the powder can be broken down over time and increase the burn rate of the powder to increase chamber pressure as you already stated.
This can be espeically true in ammo that has air in the case allowing the powder to freely move. A slightly compressed powder charge will not move as much while tumbling but still I would not recommend it.
What ammo are you looking to polish up?
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