RE: calculate my foc!!!!
FOC
All measurements are from the bottom of the nock groove.
With broadhead on, find the balance point of the arrow. Measure from nock groove. Wright this number down.
Arrow length divided by 2. Subtract this # from the balance point #.
Then divide this # by the arrow length. Multiply by 100 to get percentage.
10% - 15% is desired.
Got this from Petersens Bowhunting Mag.