Outpost75 had mentioned once that you could freeze boolits with a small amount of antimony and the result would be tough and hard; see post #15 here: https://castboolits.gunloads.com/sho...=1#post2650916
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I made up some alloy that is 50:50 COWW:SOWW, and fluxed it with 0.2oz Rootlill per pound of lead. I casted a few bullets in June and froze them until August. In September I casted more bullets, but did not freeze them (this lead was more aggressively fluxed to get another 0.1% copper in the alloy). The bullets that were not frozen were pan lubed in a toaster oven, covered in foil. The frozen boolits are significantly harder than the bullets kept at room temperature.
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I did not closely follow the recipe from Outpost75. I used a different alloy, I towel dropped the bullets, and then placed them in the freezer before they ever got to room temperature (about 15 minutes after I finished my casting session).
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I took a hard bullet with a reasonably sharp base and a soft one with a reasonably sharp base. I pressed the edges of these two bases together, and the bullets that were frozen show absolutely no marking but the room temperature bullets show a deep depression. If these two had similar hardnesses, they would have similarly deep depressions.
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Does anybody else have experience freezing bullets very soon after casting?
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