Unfortunately, I cannot answer your question as to what loading to use, but, whatever you do, I would NOT mark the sights! It will be easy enough to keep a notebook. It was intended that the lighter carbine load be used in the cadets, but no one has ever mentioned a difference in the "R" sights to accomodate this. Some have suggested that the front sight height may have been made different to achieve the purpose, but that has apparently not been researched either. My thought would be that the cadet arms were utilized more for drill and learning the manual of arms than for long range shooting. I SUSPECT that the sight issue may have been only marginally addressed, if at all. There are tables of trajectory in the original manuals, which have themselves been reprinted. That may prove helpful.