I recently ran across some garden tractor wheel weights. They are 10" in diameter and 3/4" thick. Doing the math they should weigh about 23-24 pounds if they are lead. They weigh about that on my bathroom scale. So I'm pretty sure they are a lead alloy.
When hold one up in the air and I hit them with a hammer they ring like a bell.
I melted one down into ingots and they don't ring when struck but they don't clink like the alloys I have. I can't explain it but they tone of the clink is different than the ingots I have I know are cast of wheel weights or the alloy I mixed up to about 10 BHN for the full was cutters I use in my 357. They don't sound like the wheel weights and Linotype blend I have that checks out at 14-15 BHN.
Using my Lee hardness tester they check out at around 11-12 BHN.
I think they are just car wheel weights cast into the 10"x 3/4" plate is why they ring.
Who's the guy that test lead on here? I can't recall his name.
I think I might send him some samples of this stuff just the be sure of what it is.
Leo