Not RB, simply 'cause I have no mould. Do load slug/shot/oversized buck (.375 & .311 RB).
I've used both Pyrodex & Black, prefer the latter. Best patterning for shot, inclusive of the buck is around 75.0 gr's. Same for the slugs & I get a point of aim impact with those at 50 yards. You can load a good deal hotter, but in my experience you start to blow patterns after a certain point.
Gun's my Grandfathers old single w/a 30" bbl.. I've used modern plastic shells with WW red wads for the shot stuff as well as all brass cases with fiber and heavy card wads & overshot retainers. I give the brass cases a start crimp on my Mec 650 & then glue the overshot retainers with data written on each. Same with slugs & that brass case.
Plastics get a stock 8 point fold for shot......I can roll crimp but I've found it to be somewhat difficult on some brands of modern cases.
Lotta fun to shoot those loads & you'll get onlookers at a public range with 'em.