If you want to try 7-1/2's on pheasants, good hard shot is the way to go. It doesn't have to be plated (though that helps a little), but does have to be high-antimony shot.
I've killed a bunch of wild roosters with high-antimony #7 shot from a 28-gauge, and only 7/8 of an ounce drops them real well out to 40 yards. There are around 300 7's in an ounce of shot, so they're somewhere between 7-1/2's (@350 per ounce) and 6's (@225) in size. They're also the same size as the British #6, which is most popular over there for pheasant shooting--which is usually done on driven birds, so not as many are flying directly away, like flushed pheasants.
In fact I prefer 7's to American 6's for pheasants in the 28, because they penetrate pretty well but pattern density is higher. But don't see any real reason for them in a larger gauge, where a heavier shot charge can be used.
John, I have been in the "hit them hard with 4s or 5s" since...well forever I guess. Where we hunt in Kansas this year the pheasant numbers were the best in eight years. Here is the rub, so many pheasants they were intermixed with the quail. Now a quail flys through a cloud of 4s like a movie star escaping 7.7s in a WW2 rally movie. So switching loads was a larger component of this season. Usually you walk the big stubble with pheasant loads, switch to trap loads for the plum thickets and edges for Bobbies. In usual times that is a pretty good plan. I started out predicting what the dog was smelling pretty well. But then those quail got far from cover and the ace in the hole "Quail Walk" had cockbirds and a few 8 point bucks this year. In short, enough cockbirds flew into my Handicap trap loads and if anything... brought more birds to hand without the big dog-chasing-a-rooster for ten minutes that is all too common with American coarse shot, high brass loads. Maybe you (I) shade the pheasants toward the front more, knowing the limits of 71/2s . But overall for me the 4s and 5s were not as decisive as the trap loads.
