To findForward/Front Of Center of an arrowfind the balance point of your finished arrow(with tip, fletchings etc.)by balancing it on a sharp edge. Mark this point. Measure from this point to the valley in the nock. To find the center of the shaft measure from the valley in the nock where it rests on the string to the end of the blank(not the insert), then take this measurement and divide it by 2. Take your balance point measurement and your center measurement and subtract the larger from the smaller(balance - center). Then take your difference measurement from the center and balance point and divide it from total arrow length. Then multiply thedecimal by 100. The eqaution goes like this: FOC=[(BP-EC)/TAL] x 100. This will give you the percent ofyour FOC.
Terms: FOC=Forward/Front OF Center
BP=Balance Point
EC=Exact Center of shaft
TAL=Total Arrow Length
For a good flying hunting shaft you want a FOC % between 8-15 percent. Hope you understand this. If not then google Arrow Front OfCenter on the web and that should give you a couple sites that explain this in detail.

Curtis