Don't be playing with your brass. Tumble it when your supposed to and then minimal handling after that. My brass come snout shinny before I start working on it, and the loaded rounds look just the same.
If your hands are very oily, wipe them off, if there is scuz on the cases wipe them off. It taken less than a second to do that, and 1 hour to do a tumbler full. I value my time and electric, so I will use my head and tumble them before I work them, and if they get dirty durrning process I have an old towel and a quick wipe.
I would never retumble, I wouldn't get anything done except for making a mess around the tumbler.
Factory rounds very very rarely touch a human hand, so I would bet the farm on that they do not tumble after loaded, because yall said the magic words "factory loaded ammo" do you think the factory is going to buy a green piece of brass? Umm no. They are going to get the newest of the new stuff. New manufactured brass to make cases out of, newly manufactured bullets, newly manufactured powder.
You won't see factory workers combing through the range for lead and being brass rats. Their powder and primers are more fresh than your Black Ice air freshner in your pickup truck.
Don't know how a case that is in a loading block gets dirty enough to warrant tumbling, even if your ocd. I've never had cases turn dirty on me, and I've had some odd ball 45lc cases primed sitting in the loaded block for over a year. Still as shiny as a cue ball.
