The profiles are comprised of ½ x 2-1/2in flat bar (top rail) and traditional handrail moulding (bottom rail) both rolled the hard way to a 5ft 2-1/2in and 5ft 6in inside radii respectively into a helical shape with a 29.9 degree pitch.
A special rolling set up was required to roll the handrail moulding (Wagner #H1244-19) the hard way with no distortion or cosmetic blemishes.
Notice that the top rail is finished off as a scroll which is a spiral, i.e. a flat bar rolled in one plane. This shape is also sometimes called a “pancake coil.” The bottom rail is finished off with a “lamb’s tongue.”