I know the standard progression of ammo in order of "power" is .380, 9mm, .40 cal, and then .45. And for revolvers it goes .22, 38 special, .357 mag, and then 44 Mag. I know I'm missing a few loads but these are the most common. My question is how do some of the common rounds for revolvers compare to ammo for semi autos? How would the best in class self defense load in .357 mag compare to the best in class self defense load in 40 cal or .45? 38 special compared to .380 or 9mm? I was looking at my Glock 23 and my Smith and Wesson 686 and didn't know which one had more "knock down power". Same thing for my smith and wesson 642 and a 9mm.