RE: Big Question About Front Of Center (FOC)
FOC (Front of Center) essentially is a measure of how much "leverage" your vanes will have to steer the arrow. If you think of a fulcrum (teeter totter), the longer the "lever" the more leverage. Your arrow works the same way. The point at which your arrow balances is the fulcrum of the lever. If you have high FOC (say 20%), that means that the center of balance is moved toward the point of the arrow. Therefore the vanes are on the end of a very long lever arm. That means that the vanes will have more "leverage" to steer the arrow.
On the other hand, if you have a low FOC % (say 6%), that means that the center of balance is further away from the tip of the arrow, relatively speaking. So in this case the vanes are on the end of a "shorter" lever arm. So your vanes will not have as much "leverage" to steer the arrow.