I like between 39 and 42 gr of 4759 with an MMP black sabot and 250 gr XTP hp. With 39 we were benchresting 4" groups at 250 yards. I can't remember the bullet drop but I think it was around 24".
Never, ever use a sliding powder scale with the gun. Weigh your charges and do not overload it as they are not overly forgiving. 43 gr or less and the gun will live forever.