Well I went ahead and tried it with the Dawn liquid soap (I did admit to being impatient right? ). Just one minuscule half drop of soap and there was a tiny layer of foam on the top after 10 minutes of test tumbling but not much more than I’ve seen in videos of magnetic tumblers running with appropriate soap.
Mind you with that little soap I might not have been getting much lubricating action on the pins, though my bronze test pieces were noticeably shinier already.
We’ll have to see what happens to my pins, I’ve never noticed any issue with my stainless steel shot using only Dawn, it’s stayed bright and corrosion free for a few years. Do you know if the pins are typically a similar stainless steel to mixed-shape steel shot?
Also, I was taught to wash my rotary steel shot well after using, and then store it in the (plastic) tumbler barrel covered by clean water in between uses. I’ve never had a problem with this, but notice you recommended drying the pins between uses?