I wouldn't use Sabot Slugs in a smooth bore slug barrel no matter what the box says. I know a few guys that use some of the slower Sabot Slugs with smooth bore barrels with rifled choke tubes in them.
I use Lightfield Hybrid EXP Sabot Slugs in both my 11-87 12 ga. and 11-87 20 ga.. Both have 21" fully rifled barrels with the cantilvers scope mounts and Leupold 2-7x33mm Shotgun Scopes on them. They'll shoot 2 1/2" to 3" groups at 100 yards if I'm up to it.
The best part about slug guns in New York State is every few years they add more and more counties within the state that rifles can be used in, which is currently about 75% of the state now. So the old dinosaur slug guns are getting left in the safes and the rifles are more afield now then ever before. . . . .thank god!
NYH!