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Main Boards => PowWow => Topic started by: snag on October 06, 2007, 10:42:00 PM

Title: Formula for determining spine
Post by: snag on October 06, 2007, 10:42:00 PM

Anyone use the formula that Morrison Archery has on their website for determining what spine of arrow to shoot out of your bow?

Title: Re: Formula for determining spine
Post by: snag on October 07, 2007, 12:04:00 PM

Anyone use this and how did it work for you? It has my 60#@28" ACS-CX at 98# spined arrows w/ 160gr heads! Seems a bit stiff.

Title: Re: Formula for determining spine
Post by: Bjorn on October 07, 2007, 01:03:00 PM

I used it and it worked great.

Title: Re: Formula for determining spine
Post by: Bjorn on October 07, 2007, 02:01:00 PM

Snag, let me qualify my post; it did not give me a number that was 38# over my bow weight@28. Are you sure of your calcs? My bow (an ACS) is 49# and the formula gave me 70# as I recall, which is reinforced by bareshafting.

Title: Re: Formula for determining spine
Post by: snag on October 07, 2007, 09:18:00 PM

I redid the calculation. Off a little.
60#@28" w/ 160gr tips
160-100=60/5=12 (add #1 for every 5gr over 100gr)
60#X1.4=84#+12=96# spine weight for arrows= 95-99# weight group