I have a Ruger Bisley 45 Colt with a 7.5" barrel. I am thinking about buying another one with a 5.5" barrel. In general it is my understanding that with open sights people shoot longer barrels better because of the longer sight radius. How big of a difference on average does this make? For example if I can shoot 1.5" groups at 25 yards with a 7.5" barrel how much bigger if any would the groups likely be with a 5.5" barrel? Brian.