On having more tin (sn)) than antimony (sb) check this thread out and start reading at post #50.
https://castboolits.gunloads.com/sho...y-Alloys/page3
I was just shooting for an economical alloy that would have 2% tin for fill out and enough antimony to give a bhn of 10. The other choice seemed to be the classic 20/1 which is not very economical.