Don't have a answer just more questions. I shoot Axis 500's with bows ranging from low 40's to mid 50#s found 30" to be the best length. My long bow is the only bow cut to center, I find it more forgiving. When I shot 2018's though it, the arrows all hit the same area, but when shooting older Bear recurves 9" inches left. I'm trying to get to a point where I can use the same arrow for all my bows, just changing broadheads. I've also noticed that I need a little less FOC for broadheads then I do for field points, just throwing out my observations. I'm still only in the mid 400's for grain weight on my hunting arrows, worry about penetration.