Hey guys looking at getting some new arrows for next season for elk. I am planning on getting the day six arrows but don't know whether to get 50 GR outserts or 100GR and whether to go with 4 fletch or 3. My question is is there a way to figure out FOC without actually having the arrow? Arrows would be the 300 spine at 28.5 inches long. Any advice would help, thanks!