[quote=LBR;3782912]I've never bothered with the formulas, and couldn't tell you the FOC of any set-up I have ever shot or currently shoot.
quote]

In trad, I find it more important to deal with over all mass. My hunting arrows are alway over 620 grains total, with close to 20% foc. But if you are just shooting at targets, all that matters is how well the bow likes the set up. Not many targets care how well the arrow penetrates.