It's hard to put in words, but to me the Glock 17 and Glock 19 have slightly different shapes to the grip. This is subjective, and I have no proof to back it up. The palm swell tends to feel better in my hands better on the G19 (while the G17 feels slightly awkward). I plan to make the G19 my next purchase (I currently have a G21). I was curious if anyone knew the exact differences in the grip shapes, other than just subjective feel.