i have recently been to gold tips web sight to where it says build your own arrow. I really like how they got that set up, at the completion of the part where you build your arrow they have a tolerance of 8 to 12 range of the foc. is there a sweet spot in that range? i am shooting a gt 500, 28.5 dl, 61 lbs and am thinking of going with the x-cutters or the 22 series pro from gold tip. Any info you got would be appretiated.