Although I've never hunted SD pheasants I've shot a fair number of WA, ID and OR pheasants. I have found that 4s and 5s don't pattern very well. If you are shooting over pointing dogs you shouldn't need that kind of artillery anyway. I've found a 1 0z load of 6s is going to kill any pheasant at any range that it is practical to shoot a 20 ga. If you need 4s or 5s to kill them - you are likely shooting too far for a 20 ga to be really effective and should go to a 12 ga.
