Arthur,
Thank you for the response. As good as always.
Do I think the chart is out of date? No. It has not been updated since the day they put it out, but why should they update? Designs have changed, but they're still using the same materials in bows today that we had 15 years ago when the mfrs wouldn't warranty less than 6 grains per pound.
Now I know you have an engineering/technical background so I will not presume to know more about this however, I have always operated with the understanding that today's designs are more durable than something from 10-15 years ago. Now, if that does not come from the materials used then maybe it comes from the way that they are being used. Risers and limbs look and exhibit different characteristics than they did back in the late '80s and early '90s.
Lets look at the AMO chart. As you mentioned it has not changed since the day that they produced it. In this instance we are using it to reinforce the perspective that today's arrows are too light based on those standards. However, could the opposite not also be said? Aren't the cams on today's bows helping to generate more energy dispersal to the arrow? If that is true then maybe the AMO chart recommendations are not safe enough either since the bows they were basing it on were not capable of producing the energy output that we see today.
Personally, I do not believe that to be the case anymore than thinking that the AMO recommendations are the absolute minimum arrow weight that a person can safely shoot out of their bow. If that were the case then I would have seen some form of detrimental effects on any of my bows. In other words, my personal experience just begs to differ.
To give a comparative example, how many folks on these forums do you think shoot at or above the AMO recommended minimum arrow weight for their bows? I would be willing to wager that a significant majority do not. Further, if a majority do not shoot that minimum weight then would it not stand to reason that we should be seeing alot more posts about excessive wear and tear on bows and or personal injury?
I am, by no means, promoting the use of ultralight arrows for any setup. Using too light of an arrow can and does lead to personal injury and damage to equipment. However, I think the question really is "what is an ultralight arrow?". I do think that the AMO's chart is a better tool to be used to determine this in comparison to just a blanket number like "6 grains per pound, etc..." since it does take into account many of the variables for any given setup. However, I think the chart needs to be "adjusted" to better represent current bow designs and the experiences expressed by many.
It sort of reminds me of the Pope and Young "Percentage of letoff rule". Can I get a little asterisk placed on that AMO chart anywhere?