The .45 colt served the U.S. military well for seven decades until the PC weenies forced adoption of the "Nato" (Nazi) 9mm.
After all two World Wars proved the Luger's "superiority" ..well it looks neat but the old Colt will take a man down quicker.
The .45 acp usually has TWICE the bullet weight and is much larger diameter resulting in more damge . .45 can also be procured in the various exotic hollowpoints and special expanding but the "rules of war" , the 9mm is really just an European .38 .
My dad served in Italy in WWII. He said he saw lots of wounded GIs who had been shot with the 9mm Luger, but he never saw a live German with a .45 hole in him.
9mm is just not adequate. The ballistics aren't that much better than the .38 S&W or .38 short (NOT .38 special) that the .45 replaced. We are moving backwards, probably because too many people think they can't shoot a .45 because of the "recoil." Bah. The recoil isn't all that bad, my 14 year old daughter can shoot my 1911A1 (and even hit what she aims at!) and she's a skinny thing.
I vote for pig fat in the hollow points, myself.