Steel works for a lot of applications, but I've been shooting various other kinds of non-toxic shot on everything from jumped ducks on creeks to pass-shooting geese for over 20 years now. If you believe steel will work as well as hard tungsten shot at all ranges, good luck.
I've also used a lot of bismuth (and similar weight/density "double-gun safe" shot) over that same time period, and have yet to detect any difference in effective range from lead shot. While bismuth is a little lighter, it makes up for it in a little more pattern density, if the weight/size of the shot charge is the same.
