I've never tried black powder, load I've been trying is 6.0 grs of Unique with a 250 cast booit. I have shot this load for 20 years in single action Rugers without a problem its mild and accurate.
But is at the gunsmith so out of my hands right now, I know the smith and trust him or I wouldn't have dropped it off.
I got this gun very cheap when I bought it SOG had a great sale going on, my wife actually wrapped it as a Christmas gift.