This thread started some months ago on AT regarding FOC and arrow weight. There have been quite a few folks, including your truly, who delved into this topic, theoretically and in practice, to see what worked and what didn't. After experimenting some myself and reading what others had found, as well as reading most of the articles on arrow lethality by Dr Ed Ashby, I've come to appreciate what archers in the past and present know about striving for high FOC and heavier arrow weight too. Dr Ashby also has some very enlightening info about broadheads - which ones and types work best.
AT thread on FOC - fairly long but a lot of good info in it.
Links to Dr Ed Ashby's published field test reports. Again, LOTS of very informative data he's compiled over almost 30 years.