Powder is tough stuff and can handle the vibration of a case cleaner without degradation. Heard this from someone who works at Hodgdon. I also came across very old and corroded 351 winchester self loading ammo. Tumbled it clean without issue. I've also Tumbled 9mm ammo over night for at least 8 hours and then pulled the bullet. The powder suffered no ill effects and looked the same. Also no powder dust in the bottom of the case.
