I tumble primed to get the ick off before sizing.
I don't like running dirty cases through the dies. One grit and you've messed up a die so it scratches ALL your brass.
If the primer pockets are cruddy, I'll size and decap and then tumble again, that cleans them up a little but not spit-shined.
But normally, it's just tumble, size, prime and load. If you have a media separator and keep your media unclogged, you should almost never break a pin.
