I did find that my thunderhawk will shoot the triple 77 powder ,but no more then 80 to 85 grains for excellent groups.I will also say that mt t/c favors pyrodex select and charges yp to 110 grains.
I am now using the noslers 300 grain full partition sabot with 95 grains of pyrodex select ,my choice is the RWS no # 11 1075 plus caps.
I also found that spit patch between shots is all that needed ,no solvents
good luck