I shoot the same rifle. I found that Swiss 3f or Triple Se7en 3f works best for me. Although Pyrodex P is another good powder, as is Goex 3f. I like to also use a .510 wad with the Bull Shop 460 grain. Be sure to try the 500 grain Bull Shop sometime. They really shoot well. I have the .5045 diameter in the UM and they stay on the powder just fine. That ramrod sending the bullet down takes time to get used to as there is none of the hard loading and swabbing that you might have been used to...