Had one of those a long time ago, wish I'd kept it. Shot a lot of rabbits, grouse, and squirrels with it.
Never tried it with slugs.
Regular Foster style slugs (Remington Sluggers, etc) should work just fine, they're made undersize so they'll shoot thru any choke with no problem. Sabot slugs are for rifled barrels so probably won't be as accurate out of your smoothbore barrel (plus they're way more expensive).
