I lucked out today, found a place where I was able to pick a bucket full of wheel weights. A bit over a third of them seem to be lead.
Here is the crux: Some are definitely lead, unpainted, dull lead color, soft, don't clink but sound dull, and cuts easily. There are others that also don't clink, but scraping them with a box cutter is a tad harder. Would this be just a different lead alloy and if so, should I sort them?