Limb,
Using the calculator on Jackson's site I come up with FOC of 10.1% But I'm not sure about the efficiency. I'm shooting an old (but still good) Darton set up at 65 lbs. (with 30" Easton XX75's 2315s and 125 gr.broadheads.) Plugging in efficiencies from 75 to 85%, I'm falling in the 50-53 ft/lb range at 20 yds. I'm guessing that's plenty, even if the efficiency is lower. How do you determine efficiency?
Threebeards