Shooting .45 OMVs, and .45 Colt loads (200 gr over 5 gr of Reddot or 5.2 gr of Amer Select), I can run a Nevada sweep in Gunfighter in about 4.5 seconds. I am not bragging, just making a point. I am an average shooter, shooting medium loads, and know that half of the shooters will beat me with their skills, not lighter loads.
Extremely light loads will have inconsistent combustion and may stick in longguns.