I was given these boolits and had one left. My friend came over and wanted to touch one off so I let him shoot into my fire wood stack with my BFR. One shot was all he wanted! He shot into the end of a seasoned hardwood log. The log is 18" long. I found the boolit buried to the grease groove in the log behind it. I dug it out and measured it. It lost .026" in diameter, now weighs 380gr's and I don't remember but know it was over 400. The hard lube is missing in places and doesn't look like it did anything except flake out in spots.
I have no idea what alloy it is but it still looks good after all of that wood. Too hard for me. No elephant around here.