I aquired a set of RCBS dies at a yard sale. Each Die is wraped in brown waxy paper and in a carboard box that is simply stamped on the side "6.5 Roberts", 1 is "Seater" the other obviously, "Sizer". My question is this, is this 6.5 Roberts Improved or 257 Roberts? I don't have a need for them but don't want to misrepresent them.