trophy hunter
Easy loading bullets... well, it depends on how easy you want, not much gets anyeasier than a Power Belt, but I really would not want to put my hunting success on of them although they work fine for a lot of people.
But for me to give you any clues I would need to know what rifle you are shooting. As you probably already know there is no standard bore size on a 50 cal barrel. They can vary widely even within the same manufacturer to some degree.
If I knew your rife make and model might be able to steer you right to the right sabot/bullet combination.
Somebody has already identified the different sabots, but I would also add that their are more sabot combinations available for a .451/.452 bullet than a .429/.430 caliber.
The next thing I would like to know is what are you hunting? I, myself, use one bullet for a deer class animal and another for elk, although that really probably is not necessary...
Next what is legal in your hunting area as far as projectiles and ignition systems... inline, sidehammer, rock sparker?
I would almost guarantee you there is an accurate combination out there - even if you are shooting conicals.
Sorry for all the questions....