and predicated on the fact that while I own a 28 ga reloader I've yet to load a single shell of any content with it, I'm told, by those that know about such things, that the reason there are no commerical steel loads for 28 ga's, no componants for 28 ga steel loads and no published recipes for 28 ga steel loads is because they are dangerous as hell....pressures in a 28 ga hull are HIGH even in the 3/4 oz lead loads and when you start tinkering with shit like the same volume of steel shot, which weighs less than the lead its replacing, that those pressure escalate rapidly to dangerous levels......levels that exceeds what the guns were built to handle, (and this is particularly true when you're sending steel down the barrel of a guns whose barrels are soldered together).
Like Dave says the 28 was never inteded to be a waterfowl gun, and thats even more true with steel loads, and if you are trying to make it into one it sure sounds to me like you better be willing to pay for stuff that mimics lead, or conversely, just have the desire to see if your hands, and face, will survive the explosion that occurs when you touch off that little 2-3/4" stick of dynamite you just loaded into your toy gun......
Obviously some people are getting away with it.....heck some people still shoot lead and get away with it.....and they will, till they don't......exploded guns and fingers and faces are not pretty things and I would think that keeping them in their present condition would be worth a little increased price for componants, (or loaded shells)...
Worth exactly what you paid for it as they say....
Steve