Originally Posted by SRH78
...How much energy does a round have and how effectively can it transfer that energy into the target. I shake my head every time someone says bigger and slower is better. If that was true, a 45 would be more effective than a 30-06 and that is obviously not the case. How many here would consider a 5.56 rifle a better weapon than a 45?...
But that's comparing apples and oranges.
There's no real comparison between a rifle cartridge at 2500 to 3500 fps and handgun cartridges at 800 to 1300 fps. At the range of velocities of most handgun ammunition, and given the elasticity of the target, there's simply not enough energy to make much difference.
For common handgun cartridges, effectiveness for self defense applications will be related to (1) how big a hole the bullet makes; (2) the bullet penetrating deeply enough to hit something important; and (3) the shot being placed well enough to hit something important.