Rifled slugs in common use = Forster slugs. Mostly what I buy are Remington Sluggers. At 100 yds from a ghost ring sighted security shotgun I dare say they're as accurate as most of the old milsurps I have shot.
Super slow motion video of Forster slugs show they actually spin from smoothbores. Whatever, they work.
I love to shoot them at reactive targets because the terminal effects are spectacular but TBH buckshot makes a better HD round, IMO.