TFox this thread is pretty interesting since I'm experimenting with ultra heavy arrows myself. I tried to build the arrows based on the recommendations from theAshby reports.In order to achievean FOC of at least 19%, I had to use quite a stiff shaft that could handle all that weight up front. I ended up with 26.5" Axis FMJ 340's with 4" helical feathers, 100grain brass inserts, and 160grain Grizzly BH's with 100gr steel adapters. Total arrow weight 675grains. It's for my 82nd set at 54# and comes to about 12.5gpp.