As for the military leaving the .45 to go to 9mm, they did so because the troops could carry more rounds for the same weight and volume. More rounds fired equals more enemy wounded or killed. This is the same reason they switched from .308 to 5.56mm.
I know the fake reason the military went to 9mm. Plus if your friend shot himself and didn’t blow his arm off, I would call that a good thing, not a bad thing. The .44 special will stop a criminal if you hit them where they live, heart, head lungs, etc. Arm shots are usually recommended for self defense. What did you expect? Your friend’s arm to fall off? What a friend you are.
“Personally, if I have to shoot someone, I want a round that knocks them down and stomps all over them!”
Ahh...you want a RIFLE! Great choice, if available.
The truth is you can drill someone in the heart with a 44 Magnum, and the blood in the brain will still allow him to shoot back for 5-20 seconds - longer if the heart isn’t totally destroyed.
Rifles have 4 times the power or more of a handgun, and might provide some knockdown power. However, a lot of deer hunters have discovered you can shoot a deer in the chest with a perfect shot, and still have the sucker run 100+ yards.
There you go. The theory postulated "more enemy killed' but the reality is that all things being equal, the .308 puts them down and keeps them down. As far as the 45ACP-to-9mm, the typical female's ability to control 45ACP recoil was a factor, as was the cost of training ammunition and standardization to NATO (read the story of the Army's push to get NATO to move to 308, then the Army backing off to the 5.56mm round).
The average soldier (in the '80's) also barely had ammo to qualify on their rifle (pistols were only assigned to a few) under static conditions, much less develop proficiency under dynamic, stressful conditions.
Today, soldiers in the box have both rifle and sidearm, but are still stuck with the training resource constraints. I and about 300 of my compadres were issued 9mm pistols on our mobilization in 2007, and very few understood, much less had developed basic pistol-handling skills.