That's really something - I've never seen so much lead from a smoothbore - but then, I don't shoot store-bought slugs.
; Those stainless 'tornado' brushes do work well - had one back in the 80's - just forgot about it & a lot of other things, probably. I do remember it being a good scraper & I don't remember scratches from it - but would not use one in an antique or damascus barrel.