I will also add, some people think handguns suck and as a result of that, they lump their effectiveness together so that one doesn't really shine over the other. I do agree that they'll all work if you put the bullet in the right spot and they can all fail just as easily. It's further compounded because most premium JHP bullets, no matter 9mm, .40 or .45 are all designed to perform about the same, they're meant to pass certain tests, that's it, so it's not a good example of each cartridges potential. The .40 and .45 have more room for growth than the 9mm does, sure they can all benefit from bullet design but the .40 and .45 have room to grow, the 9mm doesn't.