I have some Vapor Blackhawk 4000 arrows. The shafts say 55/70@30". What data do I enter in the dynamic spine calculator for these arrows?

ttt

Blackhawk Vapor 4000 have a .350 spine deflection at 28" centers.

350 spine and 9.9gpi i think

Thanks! One more question. When you say 350 deflection, do you mean AMO/AMA(2# @ 26") or ASTM (1.94# @ 28"). These two measurements give very different results in the spine calculator.

Use the 1.94 @ 28" for carbons.

SlowBow, Is that a general rule of thumb for carbons? In other words, anytime I use deflection for spine in the calculator, I should use 1.94@28 for carbon arrows. I would assume that the other one would be used for wood and alum.

Now I have another question. How do I convert ASTM to AMO? The spine calculator wants an AMO input.

Never mind the last post. I'm getting old and my brain just shuts off once in awhile. I need to read the calculator labels before I ask a question.

wow, you finally realize your old now? I thought this day would never come. It's best for all of us. Keep them arrows flyin old man.