Generally the higher the better. If you are shooting fixed heads, high speeds, or both......then it really begins to matter. I'm using 100gr brass Muzzy inserts in my arrows for the new Destroyer, along with 100gr GrizzTricks, and should be around 17.5% FOC. That is pretty high, but these are large cutting surface fixed heads, and they will be going at around 290. The arrows I hunted with earlier this year were going about 280 and had about a 10% foc. I was using a 100gr rage head. They flew great but Rage's always tend to, no matter what the FOC is.
Well right now I'm shooting 100 grain Montecs and my arrow weighs in at 35o grains. Now how do I calculate Foc?
Taken directly from Easton's site: AMO-Standard F.O.C. balance formula F.O.C. % = 100 x (A-L/2) L L= Correct Arrow Length-Distance from bottom of nock groove to end of shaft A=Distance from bottom of nock groove to finished arrow balance position (includes weight of point [+ insert], nock system and fletching) Essentially, measure your arrow shaft from the bottom of the nock grove to the insert. Divide that measurement by 2 (to give you your midpoint). Then WITH the BH/tip installed, find the balance point by placing the arrow on an somewhat pointed object (much like a fulcrum). When the arrow balances out front to back, measure the distance from that point to the bottom of the nock. Subtract that number (the balance point) from the midpoint measurement). Multiply that by 100, and divide that by 100 to get your FOC %.
I have been reading with great interest the testing of “Extreme Forward of Center” arrow penetration reports produced by one Dr. Ed Ashby. He concludes that 19% is the beginning of EFOC and where penetration has an exponential increase (all other arrow factors being equal). This is information I refer to as “Modern Traditional Technology”. His research also concludes this technology had been “lost” with the advent of compound bows as the speed race began the widespread use of light arrow materials. The old adage about “premature nose-diving” with high FOC turns out to be false. The current archery flight record (ultimate long distance shooting) is held by a fellow who shoots EFOC arrows. Data is beginning to trickle in that accuracy also is improved with correctly spined shafts and EFOC. The down side is an exaggerated trajectory. Perhaps, in the future, we will have the archery equivalent of the 375 H&H Magnum, a bow that will cast a 600 grain arrow at 300fps. Until that day, one must decide what he is willing to live with.
