I build mine with a straight line linear taper from the end of the pro taper to the joint but that doesn't allow me to use cool words like "parabolic" to fool customers into thinking it's really special. I also grow my shaft .010" over the pro taper. Shooter doesn't notice as it feels and looks straight.
JC
Not to pick, but the term parabolic was used by Kersenbrock to describe a taper that had a continuous curve from tip to joint. It can and has been argued that the specific terminology wasn't correct, but that's beside the point. He wasn't trying to fool customers into thinking it was special, only using a descriptive word that most people understand. The argument has been that his taper wasn't a true parabola, which IMO is getting way off into the weeds and unfair. When I hear the term, "parabolic taper" I know it means a continuous curve from joint to tip, which is notably different than a pro taper, which is notably different than a conical/euro taper, which is notably different than a compound euro. Those are all the basic taper shapes we see in shafts and the terms accurately describe the shape. Not meant to fool anybody, only inform them.