Was your Hawken new or used? Even if new, the barrel needs a good cleaning before firing. If used, a good bore cleaner, such as Shooters Choice Black Powder Cleaning Gel, and a brush of the correct caliber, to remove fouling, such as lead, plastic, copper, etc. Follow this up with a good scrubbing in hot soapy water. I shoot many T/C percussion and flint models. Goex Black Powder works best for me. I mostly use a .490 round ball, and .018" pillow ticking patches, in my .50's. Try Goex FFFG, 70,80, and 90 grains, or 80, 90, 100 grains of Goex FFG, in your Hawken, with a patched round ball. Be sure to wipe the bore of all lubricants, before a shooting session, as this can lead to fouling, and poor accuracy. I never had any luck with Maxi-Hunter's, in my T/C ML's, but PRB's shoot very accurately. IMHO if you try Goex Black Powder, you will not go back to Pyrodex.