Yeah, 6's and 7's work great on pheasants in the 28 (or any gauge), but they work better if they're hard. They don't have to be plated, but high-antimony shot definitely penetrates deeper than "standard" shot, because it doesn't flatten out when it hits.
Hard shot costs more, whether in factory or handloads, but using hard shot a size or two smaller than standard shot provides a denser pattern and penetrates just as deeply. But I know a lot of people who refuse to pay for better shot, just like many people refuse to pay for better rifle bullets.
