Depends on what you want to achieve. The MLAGB published the powder and load combinations used by the winners in the 2002 championships and .44/.45 revolvers were all around 14 - 16 grains TS2 or Goex, with one I believe at 11.5 grains of Swiss #2. These would all be round ball as MLAIC rules mandate this for revolvers. Unfortunately that document appears to be no longer found on the MLAGB website so there is only my memory to go on.

It will depend to some extent on which powder you use as powder performances vary.

I find 16 grains of Vesuvit LC or 18 grains of TS2 (with semolina filler) to be about right in my ROA. 22 grains certainly opens out my groups and I have not tested higher loads for accuracy.

It is entirely possible that there are other loads which also give good accuracy, and like with smokeless, personal preferences also seem to come into play.

One thing we can probably agree on is that a full chamber (about 40 grains in ROA), while not dangerous, is unlikely to give best accuracy - it does however give a big grin