Rich,
I do things by eye (visual appeal), not by formula.
The "golden mean" actually is a perversion of ancient Athenian philosopy which asserted that the ideal form of human being was the average (mean) person. If the gods had some other ideal in mind they would have made us that way instead. The term "golden mean" was used to indicate the ideal average in personal traits (height, weight, size of body parts, etc.). That's why you never see an ancient Greek statue of a fat or skinny person or one "over-endowed" with some particular trait.
In Greek architecture there was also a facination with the 3-4-5 right triangle. The dividing line between mathmatics (geometry) and philosophy was very vague at that time. This led to an architectural tradition of basing buildings on a 3 to 5 ratio. Most ancient Greek buildings have length to height ratios of 5 to 3, for example. Some how the architectural ratio started getting called the "golden mean". Its kind of funny, actually.
As for the length of the lowor forestock, I think rifles look best when the distance from the trigger to the butt is the same as the distance from the trigger to the entry pipe. That's just my opinion. However, I strive to achieve that look on all my guns.
Best Regards,
JMC