A couple of weeks ago I was given a 5 gal bucket of wheel weights. I saw a lot of the stick on weights in the bucket and thought I would keep those together. This morning I melted all the wheel weights and waited 8 hours to record the hardness.
What I found was, odd. I see a lot of guys post that stick on wheel weights are pure. Well that is not completely true. A lot of the stick on's that I had were zinc. In fact all but 10 pounds of the stick on's were zinc. Out of the 10 pounds of lead from the "good" stick on's, they were indeed fairly soft. They score between 7-8.5 BHN. When you drop the ingots they have a slight ring but not much. If a guy got a bunch of them I am sure they would make fine RB's or conicals. I plan on testing them as conicals.
The rest of the WW's were the clip on's. I found that a few of them were zinc as well.
I kept the melt hot enough to melt lead but not hot enough to melt the zinc. I skimmed the zinc and tossed them.
The clip on WW's were "softer" than I expected. I got 10 BHN, the same as 20-1 lead. These rang when dropped, but not as much as some of the real hard lead I have. I don't think I will be using them as conical lead but I might try some for a test.
I know that the older the lead gets it does get a little harder. It will be interesting to see what they are in a month or so. Ron

Well I have shot wheel weights with good results, but they are a harder consistency then the pure lead. The pure lead runs 5-6 BIN I was told. You might find the wheel weight roundballs load a little different. But like I said, I shot them many years ago, and they shot fine.

On my Tester it says pure runs from 5 to 8 BHN.
I don't shoot many PRB's, I shoot mostly conicals. The harder stuff I will save and make pistol bullets later. Ron