Shot placement, shot placement, shot placement....
Caliber doesn’t matter.
A hit with a .22 is better than a miss with a .45.
While shot placement is mandatory, I don’t believe hits are impossible with 45’s or that pellet guns are sufficient.
My everyday carry is 9mm, though I do carry a 45 in the winter (it’s harder to conceal in my speedo).
There's a joke in there somewhere...but I'm not going there.
Well maybe a big one.............