Mike - I think I went through Amarillo once, years ago. I'm in mid-coast Maine and haven't been out of the state for years except for Thanksgiving with the in-laws in Massachusetts, tolerable because I get 3 mornings of duck hunting out of it. How few shells do you have? I might be interested in working something out by mail. I'll ask around at the gun club for 3 1/2 inch hulls.
jOe - Were these bismuth loads matched to lead by volume or weight? The supplier of my bismuth did suggest a slow powder and low pressure to minimize stress on the shot.
lagopus - Thanks for the input. I can see a complete answer will take some research. For now I guess I'll look at something slower than 700X, I've got a bit of Universal Clays on hand, time to check the data.