According to Investarm, the max load for PRB is 90 gr. of powder. For heavier conicals it is 80 gr. I wouldn't be shooting any more that that, altho it seems to be too conservative. When I was shooting the 240 gr. conical with 80 grs of Pyrodex RS, I did not notice any recoil, and I would notice if there was much. Sam Fadala would probably want a little more powder behind the RB.