There seems to be an impulse to make a simple problem complex. With all due respect to the fine points of the Ashby data, I think the key elements are weight and quality of arrow flight. My buffalo arrows are ipe with 145 gr Eclipse heads. No, that's not extreme FOC, but they weigh 1100 gr and shoot through buffalo, from both my #80 and #86 recurves. Ipe can be hard to find, but if you contact Joseph Myers through this site he can get it for you. Off to hunt bears... Don