Thanks CherokeeKC. So my arrows are 30 3/4 from base of nock to tip or 29 1/4 to base of point. For this purpose, is the arrow length measured from the back of the field tip or the very point? Depending on where I measure, my adjustment would be anywhere from 5# to almost 15#. If the higher, then the spines come in much lower like 25# to 36#. Might this explain my snapped arrows? If there is only a 5# adjustment then I'm fairly close to where I want to be at. I think 40# spine would be ideal.