I have a .50, although I haven't worked up a hunting load for it - yet with grease or oiled patch.
I have worked up loads for other guy's .54's- back in the 70's and 1 in the 80's. Those are used
in the same areas I hunt & 120gr. 2f worked just fine with a 10oz. denim patch and .535" ball.
In the 70's I did not know about Track's mink oil or neetsfoot oil, so we had a definite problem with
an oil for cold weather hunting. I tried baby oil and vegetable cooling oils with less than stellar success.
By the 80's, I was using the totw Mink Oil with success. I see the local Princess Auto has mink oil. It smells as
if it might have petroleum in it, but that is not on the ingredients list, so I may try it.
The greater powder charges give much flatter trajectories - pbr of out to 125 yards (if sighted correctly), where centre hold is taken.
The .58's I played with having 48" twists (English Enfields) shot best with 85gr. 2F and .575" balls. The 72" Zouave I had, liked 140gr. as-did
my 66" twist Bill Large bl. on my first 'real' Hawken replica.
Not much recoil compared to the .69.