Stanton, the ratio was an accommodation to the difference in density of steel and lead. I believe the balance of choke to parallel was as a result of research done by W.W.Greener. Having said that the only Greener "Far Killer"i worked on had long taper chokes with no parallel at all. Similarly an original Stephen Grant I worked on had only taper chokes and threw very dense patterns. Regarding Eightbores observations I can only attribute his good fortune to just another of the vagaries of choke. As they say your mileage may vary.