Quote:
Originally Posted by Frank Srebro
This seems to discount the theory whereby a taller shot column - as with the same weight (mass) of bismuth vs. lead - will result in increased pressure due to more surface/friction of the shot against the bore, as the shot is accelerated. Just sayin.
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Where is the evidence of that? Do you believe that surface area of the shot column against the bore has no effect on pressure?
Case in point. Sherman Bell's data for the Short Ten shows a Fed Hull, Win 209 primer, 32gr of SR7625 with SP10 wad and some filler for both 1 1/4 ounce lead and 1 1/4 ounce of Bismuth. The lead load uses a folded crimp and generated 6700 psi. The Bismuth load using a Roll Crimp (which reduces pressure) generated 7100.
I suspect if that Bismuth load had used a folded crimp there would be somewhere around 1000 psi greater with the Bismuth.