Trapdoor Cadet advice?

I acquired this Cadet model and have found a smokeless load that will work well (for my standards) , putting 5 in 2" pretty consistently. This rifle is equipped with a Buffington, "R" sight and has a very good bore. What I would like to know, is the original arsenal load for Cadet rifles the 500 gr standard load or was it the 405 gr carbine load? Is there any data on the ballistics on the loads this rifle was intended to be used with? My intent is to see what I can do with it at mid ranges. Luckily, I have my own clanger range of 10 targets out to 700, not so lucky, it is in steep brushy terrain. Assuming the sights were calibrated to the original ammo (big if)....I could attempt to clone the load to match the sight graduations, and do a little homework with ballistics programs....eventually using the sight more or less as it was intended. It may be a fools errand. I might have to borrow someone's alfalfa field and work out to 700 marking the sight as I go. Any input will be welcome, thanks, Paul

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.