The 357 Sig was an answer to a question nobody asked. As Chuck Taylor (I believe) said, "I never knew anyone who was ever in a gunfight who wished he had a smaller bullet." The 40 S&W works just fine. The 357 Sig was a marketing effort, designed to piggy-back on the mystique of the 357 Magnum revolver cartridge. There is NOTHING to indicate that the 357 Sig is any more effective than the 40. Yeah, yeah, there will be the "I heard about a guy who..." stories of Herculean "stopping power" of any particular round being discussed, but the bottom line is a fast and accurate shooter will always win the day...regardless of the ammo. Anyone want to face down one of my Navy SEAL friends who are carrying simple 9MM target ammo? Train and practice.