I resize, SS tumble, I anneal every so often, and have tried dipping my case necks in graphite. Also when I was competitive shooting I was big on moly tumble coated pills. I never had a problem with neck tension I have no scientific proof to offer that it works any better than tumbling in rice, corn cob, red coated walnut shells lizard bedding, ninja throwing stars, or soda can pop tops. I do know that it works for me. I don't have any unexplained fliers. I can't say whether it's the annealing, the graphite, the bushing die, the stainless media. But for the best internal and external cleaning you can't beat the wet tumble.
I got out my best magnifying glass and was looking inside of my 308 case necks for any brass damage. It would be the worst case because of diameter and velocity of the SS pins. I couldn't see any denting inside or outside the case. The outside could be feasibly be getting a 6 inch drop. But you have to add in water cushioning. So sometimes you have to wave the BS meter