I wanted to paste the copied spreadsheet (text only) here but the flushlinger formatting won't hold still!

I'll get it but in the meantime it turns out the alloy calculator spreadsheet I was using didn't calculate BHN the way I normally do :

Basic Rules for Hardening Lead-

Lead = BHN 5

For every 1% additional tin, Brinell hardness increases 0.29

For every 1% additional antimony, Brinell hardness increases 0.92

For a simple equation,

Brinell = 5 (Lead) + ( 0.29 * Tin ) + ( 0.92 * Antimony )

Using the above I get a BHN slightly better than 17 for my original alloy. So the copper added more like 3.

By my calculation I added 3.5 pounds of CuSO (where you shouldn't count all of that weight towards the total weight of the components of the alloy as a lot of ash is produced) which came out to (at 25.47% copper in the CuSO) 0.89145 pounds of copper. For the finished alloy that's around 1.54% of the total weight.

I'll probably end up just taking a picture of the charts and uploading it . . .