Gitsum,
Here are the percentages listed on the MSDS for thiis particular solder,
INGREDIENTS: %wt/wt :
Tin 60 – 100%
Copper 1 – 5%
Bismuth 1 – 5%
Silver 1 – 5%
You can find it listed for almost any brand by looking on their company site and finding the MSDS sheet. They might not be down to the molecular level but they are plenty close enough to get where you looking to be.
Also you need to go to one of or both of these links and download the Excel spreadsheet calculator as well. As with the MSDS sheet, it might not be exact, but it is close enough to get you where your looking to be with your allow. Surely better than a shot in the dark.
Lead Alloy Calculators 011512.zip
The Cast Bullet Association Downloads
The first one is the one I have been using, but the second one if also a very well put together one as well. Just depends on how much you want out of them. The best thing I have found is a way to get a repeatable very close BHN allow from using quite a bit of the different purchased alloys I have gotten over the past 6-8 months. There isn't much guess work involved, simply put in the weights, and play with the numbers until the BHN I am looking for comes up. Then weigh it out and smelt it into ingots. Combined with the excellent info posted by Glen Fryxell on the LASC site, "From Ingot to Target" or in the Cast Bullet Notes section, "Cast Bullet Alloy / Alloy Maintenance", I doubt there isn't much you cannot do with your raw alloy, and the right additions.
I usually take a Lee 2 cacity mold and pour up several test boolits when I make up a batch. I throw them in a zip lock with the date, temp poured, and approximate final BHN listed on it. Then I will check them after an hour, a week and again in two weeks. I am using the Cabintree Tester and have found that with doing things this way I have been able to keep my hardness as measured with it to within around .005 or so of the dial reading. This is plenty close for the boolits I am using in my revolvers.
Hope this helps.