Range,

If you were to have a neutral FOC you would have a very unstable arrow. If you were to shoot an arrow with a neutral FOC you get into an area where the arrow would have the tendency to tip stall, possibly porpoise while it flies. With mechanicals you could shoot a much lower FOC and a smaller fletching if you wish. In fact I know an archer that shoots ACC's with a 3" fletch and mechanicals with very good accuracy. As far as the dropout at a higher FOC, that is caused by the arrow flying at a greater tip low attitude exposing more surface area into the oncoming slipstream causing more induced drag. The more drag the faster the arrow slows and drops out.

Bareshaft tuning IMHO is more of a traditional tool in testing proper arrowspine. Also you will note that when bareshaft testing is accomplished the arrow does not have a neutral FOC. Shooting an unfletched neutral FOC shaft would be very unstable, chances are that there would be little or no tip weight.

Aim Hard!