I’ve been watching a lot of Ranch Fairy’s videos and also communicating directly with him. He’s shown that heavy, high FOC arrows work extremely well and penetrate well even in tough quartering to shots, through bone and tough hide, and out of low (40 pound) draw weights.There's some really good vids on heavy arrow building/tuning. Check out Ranch Fairy on youtube. Or grizzly stik. I just got done building a dozen Gold Tip hunter xt's. 555 grains total weight, 16% Foc. Using 100 gr brass insert and will be using the 125 gr Strickland Helix. I shot the bare shafts through paper at 5 yds and was able to get them shooting bullet holes just by nock tuning. I never realized it would make such a difference, but I'm definately sold. Can't wait to hunt with them.
While he does tout the greater effectiveness of heavy/high FOC, he warns not to get hung up on any particular weight/FOC goal. What he has stressed most is that arrow flight is more important and that a straight flying arrow will penetrate better than one that is not. Mess around with insert and point weight and find what flies well.