The Springfield XDs in .45 or even smaller is the Kahr CM-40. The Kahr CM-40 is the size of a lot of .380s and even smaller than some. It's the most firepower you can stuff in a pocket size pistol (ALWAYS use pocket holster!). It's NOT fun to shoot but when the chips are down and you need absolutely the most firepower you can get in that size, it fits the niche perfectly! After conducting extensive penetration & expansion tests on different cartridges on a variety of test medias, the .40 produces about roughly twice as much damage as a .380.