RH,
Yes, I weighted everything separately and together to track down the source of the problem. It definitely was the weight tubes.
Mixing and matching heavier and lighter components didn't work because the tubes were just too far out.
Using the trimmer line to boost weight, I was able get six arrows within two grains. They tuned great and are more accurate than I can shoot.
These are some Beman ICS 400's that I used to build heavy weight arrows along Dr Ashby's guidelines. I was surprised at how straight and consistent they were. They measured better than advertised tolerances.
I don't remember what size trimmer line that I used. If I really worked at it I could force four strands into the arrows, but three was a much better fit and plenty heavy enough.
I'm obsesive compulsive about arrows and take all the steps available to build them to match as closely as possible. Probably a waste of time for most situations, but I enjoy it and it gives me confidence in my equipment.
Hope this helps,
Allen