Dave, I have a .54 caliber T/C Renegade. I have great luck with the T/C Maxi Balls and Maxi Hunters but I never used that much charge under them. Mine shoots best with 80-85 grains of Pyrodex RS powder. I also use a wonder wad between the charge and the conical. The reason for the wonder wad is The Maxi is a flat based conical, and the wad produces better gas seal and pressure, hence a more even ignition of the projectile out of the barrel. If they were hollow based conicals the wad would not be as necessary. The cornmeal underclocked was telling you about would have the same effect. Some even claim the cornmeal cleans the barrel a little on the way out. Who knows.

The rifle will shoot sabots, but I never had a lot of luck with them at long distances. Besides the first deer I shot with one (when they first came out everyone had to try them) the devil took a direct hit and ran off. I almost did not find it. That's when I went back to round ball.

Round ball are very accurate out of the rifle. 70-80 grains usually produced excellent results. I shoot Hornady, Speer, and now my own cast .530's. I use a .015 patch with water soluable oil combination I mix, also called moose milk so I was just told. If I am shooting Triple Se7en I use a wonderwad with the round ball. T-7 will smoke the patches for some reason. Pyrodex on the other hand will not. I have taken LOTS of deer with round balls, all the way out to 80 yards. Three deer this year learned about round ball all over again...

I also cast LEE R.E.A.L. conicals. They are 300 and 380 grains. I lube with bore butter. The rifle shoots them fantastic. Again, with 80 grains on the LEE conicals.

I think if you lower your charge a little, and if possible throw a wonderwad in there you will be surprised at how much more accurate the rifle becomes. The max charge of that rifle is 120 grains. I never get close to the max. And not to worry, 80 grains and a big Maxi Hunter will do the trick on anything you might want to shoot....

Good Luck