I have a couple dozen Herter's aluminum arrows cut to 28 1/2 inches that weigh 420 grains without a point and spine out at 73 on the spin-o-meter. The arrows have adapters for glue on heads. I would like to use these on my lighter setup and was thinking I could reduce the spine by using the PDP weight system from 3R, but have no idea what the shaft size is on those arrows. Does anyone know whether a 5/16 or 11/32 adapter will fit those arrows? My thinking is that if I can get the spine down to a 45# draw weight by adding 100 grains or so + a 125 gr head that I end up with a pretty heavy arrow with good FOC. It won't go very fast but should get good penetration.