My T/C 209x50 shoots the best with 80 loose grains of Pyrodex FFg with 248 grain Hornady Sabots. If i don't have any loose powder i find that you need to use more with the pellets. 110 gains with the 248 grain bullet.
I do not own the Hawken's yet. But some day.
With all three of my ML i find the loose powder to shot the best.
If i am not shooting sabots i always use a pre-lubed wad with conical bullets. I had a friend make up some soft 540 grain loads. He used the same mold that he makes is 500 S&W loads in.
540 grains with 150 grains of pellets shoot nice and pack one hell of a punch. On both ends.
With your Hawkens i would stay between 80 and 110 grains of ffg.
My BP Loading manual recommends max load for the Hawkens 110 powder volume = 109.6 grains of ffg powder.
You can also call T/C and ask what they recommend.
very good service and helpfull.