Had a buddy just die this spring. I hunted with him for about 14 years. He hunted with a 28 regularly for pheasant here in Kansas. He used an American Arms O/U that he had sawn the chokes off of and shot only #9 shot in a 3/4 ounce load. Almost every bird hit the ground dead. Cleaning them was another thing.
All of those listed above are 1 ounce loads. In a 28 that is ouchville. Nobody so far has said the shoot a 28 on wild Birds. Well I do, and here is what I found. I shoot mostly 6 shot and 7shot. Yes 7 shot not 7.5 shot. I shoot O/U's and I use 7 in my first barrel and 6 in the second. These are 3/4 ounce of shot, standard 1250 or 1275FPS loads. To me it all depends on which type dog you are using. a Flusher and a Pointer. What your choke selection will be.................Bob