I’ve found that a small bore shoots a much tighter pattern than a large bore. This being said, stringing shot is not conductive to wing shooting without a lot of practice. I did know a couple of wing shots that were pretty good with small bores on clay pigeons, and quail, but they shot little else, and shot a lot of trap with their small bores.
I think smaller bore muzzle loading smoothbores work fine on turkeys because they are rarely wing shot, and the primary target area is the head, whereas waterfowl are pretty much always on the wing, and some are incredibly hard to kill cleanly.
I hope to build a couple small bore smoothbores, one in 24 gauge, and another in 28 gauge, I do have another new old stock barrel that measures about 47 caliber (whatever gauge that works out to, that I may also use.
Hungry Horse