While I have not had the time to plug through most of the math behind the GM, mostly I have seen ists use in comparisons of width vs length and not in linear use. Many claims of its use in art have been overthroen by studies that show ratios more on the level of 1-1.5 or so. Use of the GM in rifle building to me would be kind of like going to a beauty pagent and measuring the women from the navel to the top of their heads and then from the navel to their toes and eliminating any that did not meet the GM (One individual claimed that humans ON AVERAGE show the GM in that measurement). Really if you look at averages out of 1000 there would 666 people that would fall within one standard deviation of that measurement, whatever that sd would be. Also I am sure you can pick out the GM proportion if you look at about any measurement. In this case the individual focused on the navel to find it. Is the navel some sort of important center of view? Mostly it is used to more or less determine plane geometry sizes for things like windows, book pages and art canvas, and often not really that. Again, width to length. It has become popular as a concept due to TV shows like Numbers and Dan Brown's the DaVinci Code. Lets just build them like they were built.
DP