looking for RB loads green mountain 50

[Bloodtrailer]

Have a new to me flinter with a 50 cal 36 inch green mountain barrel 1-70 I'm looking for good round ball loads -target \hunting Pa white tails. So far .490 rb with .018 patch 65grns fff seems best, but to seems easy to load, .495 w .015 very hard to load poor groups.