What is more powerful 40 or 45?

Answer 1

.40 is the more powerful

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I would have to beg to differ on that one. The highest energy .40 S&W round produces 500 ft/lb... that's the 155 grain Guardian Gold @ 1205 fps. The 200 grain Speer Gold Dot in .45 ACP produces 518 ft/lbs, while the 185 grain bonded defense produces 616 ft/lbs. So sure, there are some .40 loads which produce more energy than some .45 ACP loads, but overall? No.