Glock 36
I'm surprised no one has suggested a Glock 36. I used to have a Glock 26, but I found the grip to be too wide, like holding a brick. And because the grip was so bad, I had no control on it without the pinky extension. Sure, it was shootable, but I developed a crazy flinch due to the significant kick on it because I just couldn't get my hands around it. So I switched to a Glock 36, which is a SINGLE STACK .45. It is much easier to grip than the G26, and way thinner. It is only an extremely small amount longer and taller, and is still much smaller than the G19 or G23. And it holds 6+1 rnds of .45, which is impressive. Extremel reliable. It is NOT a pocket gun, but can be used for ankle carry, and works IWB very well. It is as slim and small as an Officer-sized 1911, but at like 1/3 the weight. Since people are recommending the G26, which is a brick and definitely NOT a pocket carry pistol, I figured I'd throw in this option. But if you really want pocket carry, no Glock fits that bill. Trust me, I tried to carry that G26, and it was just too damn wide and fat. Was decent as ankle carry, but that is sort of pointless, and G36 does that just as well, but is much easier to conceal IWB due to slimness. Pocket carry is definitely land of smaller hammerless revolver. Good luck.