Front load, how much centercut a bow is, do you shorten the shafts or not, drawweight/lenght, shootingstyle.... there are many variables that make an arra fly straight.
From my 45 lbs@29" hybrid longbow I shoot GT traditionals, 30.5 BOP, 100 grains fieldtip, factory insert and nock. They bareshaft to perfection at 20 yards. GPP is 8.6, speed is burning feathers
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BTW; here is the conversion table:
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
So a 1535 actually has a static spine value of 53. You can adjust the dynamic spine with... oh well you all know the drill....