sport -- If you are talking pheasants, I normally shoot 1-ounce loads with No. 3 or 2 steel but I have shot some over pointing dogs with the 1-ounce load of No. 4 steel.
Roster did some research on pheasant steel loads and here is a link to some of that info. Basically, #2 steel did better than #4 or #6 steel at all distances and he speculated that #3 steel would be an effective load.
http://www.nodakoutdoors.com/forums/viewtopic.php?t=67889
I would stay with spherical pellet steel loads, not mis-shapen pellet gimmick loads like BC or BS, and I'll include HS as a gimmick load, too.
Here are some pattern numbers from a 20-gauge Browning Citori with 28" Invector-plus barrels and Briley flush chokes to give you an idea of what you might find (patterns average of five, 30" post-shot scribed circle, yardage taped muzzle to target, and in-shell pellet count average of five).
20 GA 3" WINCHESTER DRYLOK STEEL LOAD
1 oz #3 steel (145 pellets) @ 1,330 fps
30 YARDS -- SK / 114 (78%)
40 YARDS -- IM / 106 (73%)
20 GA 3" REMINGTON NITRO-STEEL LOAD
1 oz #2 steel (118 pellets) @ 1,330 fps
30 YARDS -- SK / 101 (86%)
40 YARDS -- IM / 99 (84%)
If you can't put the pattern on the front end of the pheasant... little else matters!!!
Good luck.