Why don't we just err to the safe side and not take a chance on tumbling reloaded ammo. Probably unlike many others, I wipe the lube off of each round using a microfiber cloth. Only takes a few minutes and I don't have to worry if tumbling is going to change my load. Really gentlemen. You go through all the steps to make the most accurate ammo that you can, then you take a chance on damaging it??Maybe a bunch of us should get together and get a educational grant to study the effects of tumbling on different powders. See if ball or flake are more or less prone to degradation than stick powders. I can think of all kinds of experiments to try.