Everyone would like for their CCW weapon to be a big hitter, but "concealed carry" means different things to different folks. If in your job, you can wear a loose shirt and call the 45 auto you have on your hip concealed, by all means do so. I would. But if you'd lose your job if someone saw that gun, you'd probably change your definition of "concealed" to mean "will not be seen or even suspected". Practically, that would limit your choices to the tiny "mouse gun" calibers -.22, .25, .32, and .380. (Maybe you could conceal a deringer of larger caliber if you were willing to settle for a two-shot gun.) IMHO, the best truly concealable guns out there today are the .380 Kel Tec P3AT and it's near clone the .380 Ruger. I believe that a gun that used a 9x18 Makarov bullet could be built to that same small size and would be superior to either, but so far no one has manufactured one of that caliber. (But it would probably take the "mouse gun" market if someone did.)