Correct guess on the heavy spine. I have a 30.5" to 30.75" draw length. This complicates getting high FOC with wood arrows for me. The heavy weight up front really lowers the dynamic spine in relation to the dynamic spine of my bow. I am also building the shelf out 5/16" of an inch to get the arrow tuned for this setup. i get an extra 1/2" to 5/8' in length with the woody weights, which allows me to stiffen the arrows up more by cutting them shorter than the 31" to 31 1/4" that I need to keep the broadhead from running into the riser before I hit proper back tension in my shot process. The heavy arrows really up the penetration and really quieten down the bow. At 15 yards and under, a 650 grain and an 850 grain arrow go to the same place when I release. The 850 grain has a little bit higher aiming point at 20-25 yards. I am able to adjust fairly quickly moving between the two. This setup is for hunting, and my thought process behind it is to allow for the most margin of error possible for when hitting an animal, as long as the angle of the hit points the arrow towards the vitals. I could get higher FOC with carbon arrows. I just really like shooting wood arrows.