Yes, TC makes Maxi-Balls, but they never shot well in my Hawken nor my New Englander, both with 1:48 twists.
Maxi-Hunters are/were also made by TC and they shot well in my TC rifles and in my Pedersoli Frontier.
Now I found the
R.E.A.L. bullets from Lee which I tried were as Mike mentioned, have a band near the front that is oversized. WHICH explains why their name is "REAL" as it stands for, "
Rifling Engraved At Loading". These shot for me about the same as Maxi-Hunters. Today their advantage would be...you can still get molds for the REAL bullets, while for me the .54 caliber ones have been discontinued.
You should also look at Hornady, both the Great Plains bullets and the "PA Conical", aka the "ball-ette".
2003 was the last time I tried conicals, as the guide for a hunt in Canada and I discussed my using a .50 caliber flinter on Moose, and I opted for the heavier slug than a .490 round ball. Since then nothing I've hunted has made me pause to consider anything other than a patched round ball, so....
LD