Maybe I should clarify my thought a bit. The .357 mag is the smallest diameter bullet yes, but is capable of producing a lot more energy than a 45ACP. Note that I said a hotly loaded .357 mag would be my minimum. But even with that you're likely not going to knocking deer of their feet and the blood trails probably won't be awesome either. The other reason I would favor the .357 over the .45 is the trajectory. It's a much more accurate, flatter shooting round. I have absolutely no problem with carrying a .45ACP for deer hunting, I just wouldn't use it as a primary weapon.