Well I tend to recommend all my bad ideas to @B P Maniac Shooter to try out for meIt might, but ball bearings wouldn't shatter like I would've expected a marble to do (apparently it didn't), and if you patched it in a smooth-bore, the steel shouldn't contact the bore. Plenty of history shooting odd stuff down the bore... chain, nails, steel shot, etc. I'm also sorta wondering if anybody tried shooting turned wooden bullets... maybe made of lignum vitae or ironwood.
These are all probably Bad Ideas that the "Good Idea Fairy" or the "Emperor Mong" whispered into the ears of different people over the years, but we humans like to experiment...
Truth be told it was Mark's videos that got me over the line when I was looking for my first smoothbore. I was interested in the history but the idea of how much fun they could be sold me.