I used 777 in the past in .38sp cartridge loading. Made a nice boom, but really didn't need the extra oompf to get lead out to 25-40 yds. targets.
I've switched to Trail Boss in everything, and still loading out of the 5lb. can I picked up several years ago.
I still have a pound of fffg Scheutzen black for my .50cal front stuffer. I guess if I had a dueling pistol, I'd be saving it for that. I have no honor to defend, so I must assume I'd be putting it to some nefarious use. Good thing I don't have a dueling pistol then.
RCJ