The Sept/Oct 1913 "American Handgunner" had an excellent article on stopping power. It was very well done. I suggest you read it, consider what style of handgun you want to carry and make your decision. The 32 acp ranked first, 72% one shot stops, closely followed by the 380, 62%, .357 mag. 61% then 22 rimfire 60%. It is an article well worth reading.