bumpo628,
Apparently there is more to the Rotometals formula. "Brinell = X + (0.3 * Tin) + (0.92 * Antimony) for "X" enter 5 for pure lead or 8.6 for wheel weights" It appears that "X" is the base metal one is starting with.
This comes from this 12-10-10 post of a Rotometals newsletter:Here
Here is the pertinent text:
Talk Back
Lead Hardening
Recently I was asked the brinell hardness of pure lead and wheel weights. We did some research and found that the BHN of pure lead is approximately 5. The BHN for wheel weights was a little more difficult to find as wheel weights differ in their chemical composition. That said, many people use a range of 8-9; we list 8.6 as the baseline BHN for wheel weights. This got us thinking, why do we receive so many calls about hardening lead? This has to be the number one question we are asked by bullet casters. So we thought, let's try to answer this question without adding to the confusion of lead hardening.
There are two metals that can harden lead successfully, tin and antimony. For every 1% of tin added to your lead you will increase the brinell hardness by .3 and for every 1% antimony you add, you will increase the brinell hardness by .92. Using this simple equation Brinell = X + (0.3 * Tin) + (0.92 * Antimony) for "X" enter 5 for pure lead or 8.6 for wheel weights. Now you can figure out exactly how much antimony and/or tin you need to add to achieve a certain BHN.
Example: 14.7 = 8.6 + (0.3 * 5) + (0.92 * 5)
Here, we added 5% tin and 5% antimony to our wheel weights and achieved a 14.7 BHN.
For more information and to look up these products, visit us online at www.Rotometals.com.
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