A while back I made a comment on someone else's post stating that I thought the 10mm had less felt recoil than the .40 S&W, given the same bullet weight and velocity. Everyone seemed to chalk it up to the extra size and weight of the GLOCK 20sf. At the time, I stated that I thought the pressures would also be less in the downloaded 10mm because of the increased case capacity. Everyone seemed to disagree with that idea. However, I was just comparing the .40 and 10mm load data on the Hodgdon reloading website, and there is indeed as much as a 5,000 psi pressure difference between the .40 and 10mm given the same bullet at the same velocity. Example: .40 S&W 155gr Hornady XTP @ 1030 fps = 28,100 psi 10mm 155gr Hornady XTP @ 1030 fps = 23,000 psi I don't see how this could not effect felt recoil.