I know my boys have taken down quite a few boar hogs using rifled slugs in my 20GA Mossberg500. Out to about 75yds, the ballistics are close to a .50cal muzzleloader.
My gun really liked the Brenneke slugs that poppgunner mentioned.
Oh, I usually left on the imp. cyl. choke when they were shooting the slugs and it never caused an issue.