The 310gr cast from TII bullets over 14grs of TrailBoss, is usually good if I do my part. You can drop back to 12grs too.
I have loaded 12grs of Titegroup and while mild, it never seems to be as accurate.
You can buy some 500Spl brass and down load a little more. On Sierra website they have loads for their 350gr in the spl. You can extrapolate for cast.
Note: I prefer to use the shorter brass for the plinking loads. While the primer pocket is for rifle primers, you can get away with a large pistol primer. I have used large mag primers for shotshells.