Black Frog, I made a very good living as a machinist and quality control inspector in the aerospace industry before I retired. So, I have the background and experience behind me to know how to check what I want to find out.

What I am checking is not kosher according to what the manufacturers supposedly guarantee, but it is critical to someone that' s wanting to get a broadhead to spin true. If the insert end of the arrow doesn' t spin true, the broadhead never will.

Same thing applies to the nock end. If the nock is offcenter from the shaft, then the string will power the arrow off to the side instead of down the center. If the nock is misaligned horizontally to the rest, the arrow will be forced sideways by the string. If the nock is misaligned vertically, it will be forced off either up or down.

You' re right that placement of the support will affect the readings. If I' d gone to 2" overhang instead of 4" , the runout would likely have been less. If I' d gone 6" , the runout would likely have been more. 4" was just an arbitrary decision on my part.