Some data show compressed. One reason to use caution is you can cause the case to deform or bulge if you compress too much. Probably affects ignition as well if it is too tight.
I found the chrony to be a great tool on pistol rounds, since you can easily get too hot but on the other hand many semi automatics will not cycle reliably if pressure is too low. As other posters pointed out, i find 1100 - 1200 velocity give reliable performance in my guns.
I learned about this when have misfeeds with practice ammo. Turned out when I shot it thru a chrony it was getting 950 fps. data had predicted 1150. Changed powder, loaded to 1150, problem solved. New chrony paid for.