Brandon,
I haven't mentioned a lot about any Extreme FOC upper limit of benefit gains. That's mainly because I haven't had time to set up and test a progressively increasing FOC matched arrow set that goes up and up, and don't know if there is an upper limit of benefit!
I have done testing with various setups having FOC levels up to a bit over 30%. The data is STRONGLY suggestive that penetration gain DOES continue to increase as the degree of FOC increases.
So, in a nutchell, here's what APPEARS to be the FOC boundries. The first noticable jump in FOC supplied penetration is around 19%. Above that level, the more FOC you have, the better it seems to get.
David,
In terms of the arrow's terminal performance; as long as everything else is equal between two arrows (dimensions and flight quality), increasing arrow weight increases the terminal performance; more mass means more penetration potential. The only limiting factor is the bow's ability to cast the arrow with a trajectory adequate for the hunting YOU do. The most critical mass-related penetration factor is the heavy bone threshold.
Arrow mass is like bow-derived arrow force. You'll benefit from using ALL YOU CAN EFFECTIVELY USE.
Ed
TGMM Family of the Bow