TexasCHLforum.com

Like CC Italian alluded to, many police departments issue or mandate the use of handguns chambered in .40 S&W. Some folks, for whatever reason, like to use the same guns or ammunition as the police. And as others posted earlier, there may be perceived advantages in competitive shooting, or they want to split the difference between the two traditional choices (9mm and .45 ACP).

I would not choose to carry a weapon in .40 S&W unless it was engineered specifically for that cartridge and not simply a bored-out 9mm, and I was satisfied with the weapon's manual of arms and other handling characteristics.

9mm, .40 S&W and .45 ACP are all capable of decent penetration in ballistic gelatin (which is simply a standardized test medium), but by default I prefer heavier and wider bullets over smaller and lighter ones for whatever slight terminal ballistic edge the former may offer.