I lived in Kansas and Nebraska for about ten years in the late 1970s and early 1980s. I hunted upland birds--quail, pheasants, prairie chickens and sharp-tailed grouse--from the day the first season opened until the last one closed. I always shot a 12-gauge in those days and I always started the season with 2 3/4" 7-1/2 shot. By the end of pheasant season, when all the other seasons had closed, I was shooting Magnum 4s with a full choke as the birds were getting up much farther away, and anything less resulted in too many wounded birds.
Since then, I have been primarily a quail hunter. However, each year I do one or two late-season preserve hunts for pheasants, as well as some mixed bag hunts in Montana, using my little 20-gauge double. I have found that 6s put the birds down more reliably than 7-1/2s.
A lot depends on how you hunt: with or without dogs, with pointing dogs versus flushing dogs. etc.
