Snag, what Craig is talking about is an "out of round" shaft. I don't see it much in the premium matched dozens, but you will find it in their bulk. There is quite a difference in the hardness of the summer growth and winter dormant wood in fir. When the shafts are sanded to size, the softer wood sands more leaving the shaft out of round. The shafts will still make good arrows, but don't make the cut for my premium shafts or customer arrows. They go in the stumper pile or get used for spine test arrows or for my arrows.
Yeah TSP, fir is tough, but when it breaks, it really breaks. I like that, tho. I've had POC and Spruce crush rather than break and that damage isn't always so noticeable. My pig arrow was Sitka Spruce, and he boar rolled over on the arrow twice. It didn't "break", but now has several permanent compression frets on one side. It might as well be broken and would be very unsafe to shoot.