Here is a chart, from this web page, which shows measured pressure changes with 40 S&W using a 180 grain projectile.
http://www.greent.com/40Page/ammo/40/180gr.htm
Overall Length
Pressure
1.140" 26,195 psi
1.130" 27,521 psi
1.120" 29,079 psi
1.115" 29,924 psi
1.100" 32,900 psi...