I should mention that, though zinc can be cast by itself with practice, its density is only about 60% that of most casting alloys, so a zinc bullet cast in a current mold for a 230 grain lead .452" round nose bullets will come out weighing a little under 140 grains. That means the sectional density will be 40% lower, too, which means the ballistic coefficient will be 40% lower, too. Same will apply to all bullets cast in molds not made for zinc. This may not seem like a big deal for 7 yard ranges with handguns, but for a lot of rifle bullets it means they won't stabilize in existing rifling twist and the powders normally used will be too slow for them.
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