New underhammer load?

[GRB]

putting an underhammer together now, 50 cal., 1 in 28 twist with a 32" barrel, will be mounting a 6 power Malcolm shortly, was wondering kinda were to start on the loads for basically elk or mulies, have a pretty good idea but would like some input from those shooting simular rifles, been using round balls or 35 years plus on whitetails. the sabot things gonna be kinda new to me.thanks