Leaning this way:
Start w/just the sights. Try Breneks and Remington Sluggers for a foster slug out of a mod and full choke. Sometimes a gun likes another Foster better, but that Slugger is usually the best for us. IDK if you will beat that with a sabot and rifled tube and a foster or a Brenek may really surprise you out of a bird gun. 2 inches at 50 yards is pretty common.
My experience with those tubes and Fosters is the first one fills up all the groves with lead w/o giving much, if any, accuracy improvement.