In my opinion, not really a lot of real world difference between .38 spl, .40, 9mm, and .45. Kinda like comparing real world difference between .308, 30.06, .270, .243 etc.
A bullet placed in the upper hydraulics will stop someone in a few moments. A round in the head or spine will stop them a lot faster.
My experience is with a .38 spl 158gr SWCHP at about 60 feet to the chest, and a .40 180 grain Gold Dot at 1 foot to the chest. Same result, they died. Neither died appreciably faster.
"Put none but Americans on guard tonight." -George Washington
