I have one of the rifled choke tubes for shooting sabot slugs. Actually one of my buddies is borrowing right now.
Anyway a few things about it. It is designed for shooting slugs like the winchester BRI type slugs and the lightfield slugs.
It is not
designed for shooting the winchester paltimun tips or similar type slugs that are basically a large caliber handgun bullet in a sabot.
Now for the results. Using open sights (tru glo gobble dot magnum fiber optics)I shot groups using the lighfields and Winchester BRI slugs at 50 yards and they grouped about 3 inches. Thats using a Browning BPS stalker with 24 inch barrel, using a sandbag.
I don't know what the BPS would do if I put an IC or cylinder smooth choke tube in it and shot foster type slugs.
the BPS and me are not getting along very well right now. I think it is a personal preference and gun fit thing.
I have a smoothbore 870 with 20 inch barrel with rifle sights that shoots foster type slugs about the same sized groups at 50 yards.
I hope that helps some.