Probably should not say, lest I be flamed, and most find 30 grains to be a good load, but in my .50" I find that up to 60-65 grains is still very accurate, with patched round ball or the "PA" bullet, but that is about my limit for recoil. I have fired it with 70 grains, but yeah, it requires such a death-grip that it's hard to get a steady hold for good aim. About the same as a .44 mag with 60-65 grains. The reason I fire that heavy of a load is that when calling cougar, I like to set my handgun on my right, so that if (and when) a cougar comes in from behind and to my right, I can shoot it better with the pistol (it's going to be close) than trying to swing around to my right with the rifle. Too much movement which will spook the kitty cat.
ATTABOY! I shoot 85 grains FF in mine. I grip it with the left hand forward near the end of the stock and consider it a short rifle. The accuracy is excellent. Makes a big boom too.