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Heavy bows? Spine rating of shafts outside the AMO standard?

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markinengland:
Does anyone know of guidance for spining arrow shafts for bows of over 70lbs?
The standard shows  a deflection of .37 to .35 of an inch for bows of 65 to 70lbs (band K). What if the bow is heavier or the shafts stiffer?
Mark in England

Pat B:
Mark, I have a spine deflection chart that goes up to 125#(.208). If I can locate it and get it to scan I will post it here or probably e-mail it to you.  I believe there is a formula to follow to figure it out but I don't know it. I'm sure someone does and will speak up.     Pat

markinengland:
Pat,
Thanks. If you could find it that would be great.
Mark

Pat B:
Mark, I couldn't get it to scan  ::) so I copied it for you and sent it in an e-mail to you. I hope it is what you want. I also sent you to a link that might have the complete chart.    Pat

Badger:
Mark, on some of the heavy bows that are using 32" arrows and 300 grain bodkins the spine might be kind of hard to figure, The point weight has a major effect on how much spine you need as does the length. A 125# bow would need about 125# spine arrow if the arrow were 28" long and the tip about 125 grains. For every 25 grains point weight and every 1" of length you need to add about 5# of spine. So you might need close to 200# spine for a war arrow. Be real curious what methods our war bow enthusuasts use to get correct spine, good question Mark. Steve

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