BH 209 and T/C Hawkens - from the horse's mouth
I just got off the phone with Western Powders. They said that a T/C Hawken converted to 209 primer ignition was safe with BH 209 powder - BUT - the maximum safe charge was 110 grains by volume.
So I'll use 90 grains by volume as my personal max and round balls only and I should be well below the max safe pressure.