Well I'll tell you, in the last couple of years I have mixed a huge number of alloys, starting with pure lead/antimony/arsenic and tin. I have alloyed with wheel weights and heat hardening and I have to tell you there is no solid formula, bullets can be hardened several ways, Antimony for one (most common), tin for another and the addition of arsenic to facilitate heat hardening. I have had the best luck so far with the addition of PbAs85/15 to reach a saturation of .75% -1% much over that and there is no additional benefit. If you use wheel weights in your mix you can figure a very maximum of .25% As content, this allows some benefit to heat treating but it will not reach it maximum potential especially if you add other pure metals to the mix. Tin provides some hardening but at a much greater expense in addition to making your bullet much lighter, this is why tin is used primarily for surface tension reduction (flow). Antimony will increase the overall hardness but due to the resulting structure of the alloy it will also cause the bullet to become brittle, the more you use the more glass-like the lead alloy will become up to the point of self destruction at higher speeds due to the bullet spin alone. A bullet hardened to BHN range in the upper 20's can shatter if dropped on a concrete floor. As I indicated before my best results have been achieved using a lead/tin/antimony mixture with a base hardness (for low pressure-up to 26kpsi) around 3-4BHN below my desired max pressure then I powder coat, size then heat treat, by adjusting my soak time I can bring my hardness right to the level I want and by choosing the correct powder I hit it with just the right deforming pressure for a good clean seal. For higher pressures I stay 6-8 BHN below my desired max pressure and using the same process and adjusting the time and temperature of the heat treating cycle to reach BHN values in the 30+ range without the inherent brittleness encountered using only Antimony. The resulting projectiles work perfectly for velocity well over 2500fps in my .223 Now you may never get 3k with the same accuracy as a copper jacket but you can with a little (lot) trial and error get very close. There are a lot of opinions about this, many for many against so take all the information you have received do your own testing and stick with what works best, if you have any questions feel free to pm me.
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