I have the same set up , my .54 Hawken did not like the Pyrodex.
I now use 90 gr. 777 / wonder wad / .365 maxi ball.

I can get a 2 to 3 inch group at 100 yds,with fiber optic open sightsand a good bench rest

TC Quit making the .54-365 gr. but you can still find them if you check around.

After my supply is gone I will try the 300 gr. REAL.

Hope this helps and let me know what you do