There really isn't any such thing as "correct FOC". It's up to each bowhunter to decide how much forgiveness they want built into their arrows. The arrow shaft could weight 50 grains with a 200 grain head, if you could find a material that would spine correctly at that weight (or if you shoot it out of a very low draw weight/draw length bow.

Were do I get the brass inserts???

http://www.3riversarchery.com/Index.asp