Yes I do think that would prevent tumbling, but with the wads I am currently using, there isn't enough room for a bolt to run through the center of it. It would interfere with the cushioning "legs" that are in the wad. I've thought about epoxying or glueing the wads to the base of the slug though, so maybe that might work. Short of changing wads though, I don' t quite know how to get a screw/bolt assembly to work.

Certainly lots to experiment with here though.