I learned pistols on a 1911 in the ARMY. I am a firm believer in a 45 as the best in a personal protection round. Pistol engagements are usually between seven out to fifty feet. You want the round to take the threat off it's feet, not to past through. I want that big piece of slow moving lead to do just that. A .38 spl, PLUS + P, I don't take the chance. Someone under the infulence of something, maybe not. A 45, YES. A 357, 9MM will pass on through up close. In the case of a 40S&W, I really don't know.