Sal...most of my selfbows shoot the same spine shaft as the weight of the bow, except for one which shot less. A lot goes into your selection of course. When choosing wood for selfbows, try and pick out the "skinniest" shafts you can, to move the effective "center" closer to the real center...does that make sense. Most of my arrows are 11/32 to less, with the exception of the hand-planed shafts or primitive shafts. Of course, I also like big feathers in the back to get things straightened out quicker....works for me with the heavier heads I shoot, and it would work for yours also. Good luck.