Any time you can get a large bore shotoing into 4" or less at 100 yards, you have a super winning combination. My groups ran around double that from the smoothbore, which I figured was pretty much the lower limit. Gil Sengle got groups with round balls from his smooth-bore 12 gauge Martini in the 3" range at 50 yards - similar to mine and plenty tight enough for big game shooting. He used undersized balls as I did, with inverted gas-check wads fro ball centering (cut from plastic trap wads).

I suspect fast twists, such as the common 35" or 36" used in modern factory rifled 12's and Hastings barrels might do better with some sort of slug, but still might shoot fine with round balls - one needs only to experiment.

Those who have slower twists may be best to stick with the round balls. I still haven't tried any of the loads I have developed for my 16 bore Husky side by side. The right tube is rifled in the slowest of twists ever cut - straight. It's 13 bore size makes for interesting looking ammo as the chamber is cut for a 16 bore hull - probably brass. Using plastic cases, the .684" ball I'm using must be glued to a wad and protrude from the case mouth. It doesn't go to the bottom of the grooves, but engraves 1/2 wad so might work. - One of these days?