I've shot some 370 gr maxi-hunters and some 385 GP's out of one of my BD's. Accuracy was OK with the maxi-hunters (about 3" at 100 yds) the Hornady GP bullets shot a little better (2-2.5" @ 100yds). The load that shot best with both bullets turned out to be 75 grs of pistol pyrodex and a CCI mag #11 cap.
FWIW, a friend of mine who only shoots conicals tried both of those bullets and some no excuses in a BD he owns and could not get acceptible accuracy (he would get 6-8" groups @ 100yds at best). He had a smith remove the QLA and crown the barrel and his gun now shoots under 2". I don't recall the powder charge he is using but removing the QLA made a huge difference for him. I guess I got lucky since mine shot fine with the QLA.