I'm just a rookie at this, but I've found the same thing that Jeff B mentioned. Carbon Tech seems to be much closer in shaft to shaft spine, and spine around the shaft than the other carbons I have. I got .002 spine around the shaft and .004 as the greatest variation within the dozen shafts, and that was with Cheetah Hunters (.006). Other all carbons varied by .014 in the half dozen I tested. Still, the results with ACCs made me question my construction of the spine meter, and the purchase of other arrows to try. The ACCs were .001 around the shaft, and only varied .001 within a dozen. They seem to shoot more consistently, but It's hard to tell at my skill level.

I'll have to check for the seam like you mentioned, and compare it with the spine around the shaft to see if there is a connection, but I'd guess there probably is.