Black Jack is on. With the Lee REAL in the slow twist, always choose the lightest weight, 250gr for 50, 300 for 54. In my old 50 CVA with 1 in 66" I get 1.5" groups at 100 by using 90gr FFg with an Ox Yoke felt wad (with a little extra lube) and a 250gr REAL. Actually shoots a little better than round balls. If you try the heavier weight for the bore, you are defeating your purpose. Slow twists demand a short projectile (RB, REAL, BallEt), as the faster the twist the longer the projectile it wants.