I've noticed on a few model 8's that the bolt carrier is cracked or chipped on the top portion of the extractor lip groove. I'm not sure exactly what causes this, maybe you gunsmiths can provide some insight, but it seems to occur in the same area on the bolt carrier on early model 8's. I don't think it's a frequent occurence, i've only seen a handful of rifles like this. It does not appear to affect the function of the rifle nor the extraction. I posted this on the other forums as well.
I am guessing that the damage may have occurred when the bolt was out of its rotation alignment, and the bolt was released in its normal fashion (see my "caution" post a few posts ahead).
It occurs to me that if someone has tried to pry the extractor out of the bolt carrier, this is exactly the sort of chipping/cracking I would expect. If the bolt head is out of alignment when the bolt is released, the locking lugs will stop the bolt against the barrel extension, while the extractor is still not near enough to anything to cause this sort of damage.