It’s been proven that a 9mm is nearly or as effective as the 45 on men. My question is which one would be better on large, heavy boned animals in today’s times?
My GUESS would be the 45.. but thats based on some old ballistics testing I was involved in during the late 90's and early 2000's.. that was NOT centered around horses.. we were shooting unarmored vehicles and other large heavy objects (everything from refrigerators to coffee tables) and trying to figure out "penetration" in terms of what penetrated deepest, most consistently, etc.. what moved consistently in straight line vs deflecting when it hit angles like a cars front windshield, etc..
What we found back then was bigger and slower generally penetrated deeper and more in a straight line across a wide variety of targets than smaller and faster..
Too slow was not good.. low velocity buckshot for example didnt fare well on a lot of the things we shot..
But generally speaking pistols actually penetrated deeper and more in a straight line through walls, car doors, etc.. than say 556 did... which would divert off path, fragment, etc.. after hitting something hard or angled.. and larger, slower pistols like a 230gr 45 ACP generally penetrated deeper and more in a straight line than smaller, faster pistol rounds like a 115gr 9mm..