I was hoping that someone here has a link to a chart cross referencing spine (50-55# etc) vs deflection measurements (.500).
Thanks again for the help
What most of us mean when talking about "spine" is actually the deflection measurement of the arrow. Not sure, but I believe Gold Tip is the only major arrow manufacturer that labels their arrows 15/35, 55/75, etc.
GT arrows also have their actual deflection rate marked on their arrows. For example, the 55/75 arrows are a .400 deflection rate. The 75/95 arrows are a .340 deflection rate.
BTW, I just looked on some new GT Traditional arrows, and they do NOT have the deflection rate on the arrows, but you can go to their website to find that info.
The short version=spine and deflection are the same thing. :)
Here it is:
15-35 or 0.600" becomes: 26/0,6 x 1,2115 = 52,5 lbs
35-55 or 0.500" becomes: 26/0,5 x 1,2115 = 63 lbs
55-75 or 0.400" becomes: 26/0,4 x 1,2115 = 78 lbs
75-95 or 0.300" becomes: 26/0,3 x 1,2115 = 105 lbs
Ad hit it on the head.
The other useful conversion I've found is ASTM deflection x .825 = AMO deflection.
So if you spine your own arrows, usually woodies are measured according to AMO (26" centers and 2# weight). Carbons are measured ASTM (28" centers and 1.94# weight)
Stu Millers spine calculator is the easiest way to convert into #spine.