Buck Magnet, I' ve found FOC with field points isn' t as critical as with broadheads. I have decent groups with 100 or 65 gr points, on the same arrows. If FOC gets too low with broadheads, my groups are not to my satisfaction. I think I' ve had as little as 6% with field points, but less than 10% with broadheads didn' t do well. I don' t shoot beyond 45 yds, usually.