As you may know, the same spring powers both the hammer and trigger return on the Redhawk. Using a lighter spring will reduce trigger pull, but will also reduce hammer impact. You may want to try ammo with different primers to be certain of ignition under all conditions.
I think EGW makes a picatinny rail for the scout that might give you more options on mounting rings.
Nice groups with the Redhawk, I wouldn't have thought that short barrel could shoot that well.