The way I've read these posts on the spine chart differential, I'd say we're all equally right and wrong in our convictions. After all, the charts are only an "indicator" for the correct spine for your individual bow/arrow system.

Because the charts are indicators, in my shop we use at least two of them plus the manufacturer's chart to ascertain where we should START. I can't tell you how many times the charts were incorrect. After all, how can a chart cover all the cam styles, limb deflections, and string elasticity. Now keep in mind that we're talking about getting something fine tuned.

We've had situations where we tried three different carbon arrows from three different manufacturers while using their individual charts for the selection for a particular bow. One might work to perfection whereas the other two fell far short.

What this is all getting to is that there are a lot of things that affect the arrow selection and minor discrepancies can put one "over the edge". By moving the weight outward by any type of "extension", you can weaken the spine. For example, a 1/4" round ball at the end of a straw will not have as much impact on the straw as a long 1/32" rod weighing the same weight as the ball. That "length" will affect the spine; but, by how much??? We must also consider the fact that the blades of a broadhead are wings that can drive the spine in any direction on a poorly tuned arrow.

If you are close to the edge of spine discrepancy and you extend the length of the weight, it could affect the spine. If, on the other hand you are at the mean spine parameters, the affect will be negligible.