I performed several gel tests a while back using some bullets John Kort, aka w44wcf cast to his specs and sent me for testing.
Some 42798 cast 75/1. Impact velocity at 50 yards was 1,162fps from a 26" barrel
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Expands just like a hollowpoint.
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The below lead bullet was one of the soft lead tests while the below jacketed hollowpoint was tested with a thumping load of 2400.
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Here is an example of lead bullets expanding just as well as jacketed hollowpoints. Once the velocity tapers off to a slow brisk walk, the bullets, especially hard casts...will not expand and will penetrate the broadside of a horse.