springer -- I've not shot any Blind Side at pheasants but I have patterned it and shot a few ducks with it. I have no doubt that you could kill pheasants with it but I didn't really notice anything special about it while shooting a few ducks.
It doesn't tend to pattern as tight as traditional spherical steel rounds (see my patterns below) but at close range it should be effective. To me, it is much like some of the other designer steel loads, marketers trying to sell you something you don't need. If you need a nontoxic load, just get some traditional spherical #3 or #2 steel loads, use the appropriate choke, and go shoot your pheasants.
Here are some of my pattern numbers comparing several steel loads to give you an idea of the kind of performance you might get from BS loads.
Patterning results from a 12-gauge 3" Remington 870 Special Purpose with a 28" barrel and factory flush Rem-chokes (pattern average of five, 30" post-shot scribed circle, yardage taped muzzle to target, in-shell pellet count average of five, and true choke constriction from bore gauge).
40 YARDS / Modified flush factory Rem-choke (.018" constriction)
Federal Speed-Shok 3" 1 1/4 oz #2 steel (154 pellets) pattern 115 (75%)
Federal Black Cloud 3" 1 1/4 oz #2 steel (144 pellets) pattern 92 (64%)
Fiocchi Golden 3" 1 1/4 oz #2 steel (156 pellets) pattern 115 (74%)
Hevi-Metal 3" 1 1/4 oz #2 / #5 (164 pellets) pattern 93 (58%)
HEVI-STEEL 3" 1 1/4 oz #2 steel (148 pellets) pattern 100 (68%)
Kent Fasteel 3" 1 1/4 oz #2 steel (155 pellets) pattern 103 (66%)
Remington Sportsman 3" 1 1/4 oz #2 steel (152 pellets) pattern 110 (72%)
Winchester Xpert 3" 1 1/4 oz #2 steel (146 pellets) pattern 106 (73%)
Winchester Blind Side 3" 1 3/8 oz #2 steel (176 pellets) pattern 104 (59%)
Here are a few more of my pattern numbers with a load I commonly shoot ducks and pheasants with. Patterns were shot with a 12-gauge Browning Citori with 28" Invector-plus barrels and Briley flush chokes (patterns average of five, 30" post-shot scribed circle, yardage taped muzzle to target, and in-shell pellet count average of five).
12 GA 2 3/4" REMINGTON SPORTSMAN HI-SPEED STEEL LOAD
1 1/8 oz #2 steel (139 pellets) @ 1,375 fps
30 YARDS / SK / pattern 116 (84%)
40 YARDS / M / pattern 114 (82%)
Hope this helps, good luck.