10mm vs 45 ACP: 37,500 psi Against 21,000
Same test barrel, same rifling, nearly double the pressure. Federal’s HST in both is 567 ft-lb against 404 — and the 10mm spans 600 fps across the catalog.
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9mm vs 45 ACP: The Two FBI Papers Everyone Cites Disagree With Each Other
Buy the 9mm — more rounds, far less recoil, cheaper practice. But the popular reason why is a misreading of the document everyone cites, and the FBI’s own earlier paper says the opposite. We quote both, because they disagree.
