They should work in a smooth bore. Maybe a bit better than a regular foster slug because they will have the tail to help keep them stable.
I would not shoot them out of a more constricting choke though because they don't have the callapsable fins on the outside of the slug.
Never know if you don't try them

. They are fairly heavy so they should have pretty good knock down power at closer ranges. The trajectory may not be that great though. Plenty for a smooth bore however.
Paul