My wife over the last two years has taken 3 turkeys with her 28 ga(.54) smoothrifle. It works for her. An 80 grain load of powder with the same volume of homemade drip shot for each one. I think the advantage she has is she was never told it couldn't be done (or that she needed a big 10 or 12 guage) so she just goes ahead and does it.
Medicine Soldier