You can read this kind of stuff until you want to poke your eyeballs out...
Here's the bottom line:
It's not the ammo, it's the accuracy.
A well placed .22LR at close range will kill somebody.
A 44 magnum at close range that misses will only make a very loud noise.
Shot placement. Shot placement. Shot placement.
Get good with whatever ammo load you are carrying and you'll be way ahead of anyone who obsesses over ammo more than they do over practicing to be accurate under stress.