Yes, they do. The carbon arrows I've checked on a spine tester all have an actual 'spine', one spot around the shaft where it's stiffer than at any other point around the shaft. I've picked up as much as .035" difference in deflection between shafts in the same dozen and as much as .025" deflection in deflection from one side of the shaft to the next on the same arrow! But they usually run in the .010-.015" range within the same arrow. Honestly, some of the worst I've ever seen have been were GoldTip Hunters.

So, before I fletch up, I sort the arrows by spine. Any that are really different from the others, I set aside. Then I orient the nocks to put my cock feather right over the stiffest area of each shaft.

It's amazing that this high tech carbon arrow BS has got us doing the same kinds of things we were doing in the middle of the last century with wood arrows. All those years of shooting aluminum and not having to worry about stuff like that got me VERY spoiled. [&:]