Black Frog, you are correct that Easton, all arrow manufacturers actually, uses a specific distance between supports. Then they check runout in the center of the shaft. Problem is, if you' re checking a 33" long shaft across supports that are 28" apart, then you' ve got a couple of inches of each end of the shaft that are not being checked at all.

So, that method doesn' t really tell you what' s going on with the ends of the shaft. My supports were closer together than 28" , supporting the shaft, with the tip sticking out 4" past the support so I could measure concentricity of the tip to the rest of the shaft. I could' ve gone 3" . I could' ve gone 6" . I just settled on 4" because that' s kinda where I wound up with my setup.