About 60 yrs. ago a hunter in our group used a shotgun with the Foster type slug. Forget the model no. but it was a Savage with a 28" full choked barrel. It would keep 5 slugs within the 8 ring of a 25 yard pistol target. It was the only long gun the fellow owned and was an excellent waterfowl hunter too. I don't believe slugs effected the choke in his barrel at all. In those shot charges were not in a cup, so as with slugs it was lead going down a steel barrel.