Hi castboolits. I work for a car dealer up north and was researching something about one of our suppliers today. A guy told me they no longer sold lead WW so I went to reasearch it and ended up on the website of a Quebec based wheel balancing weight manufacturer, Plombco. Of special interest to me was the fact that they had a MSDS sheet for their product. Usually these include what the composition of the product is. Here is the link for their lead WW : http://www.plombco.com/files/media/M...Weights%20.pdf
You will probably remark that they list iron as a major componenent of the WW's. Come to think of it, the clip is actually made of iron and is a component of the product they make, hence why it's between 2 and 20% by mass of the actual finished product. I dont know if these are based of tests they run but I'd guess that these are some average numbers. The lead alloy components should therefore be : Pb +- 95%, Sb +-4%, As +-0.30% (I know, that doesn't add up to 100%...). So here it is, this is what this particular manufacturer claim their COWW are made of.
YMMV.
Frank