I'm not defending PTG outright as they've cocked up a LOT of stuff for me BUT!
This is likely more the cause of a gunsmith reaming a chamber with a floating holder that wasn't "floating" properly than it was PTG's fault. Typically their reamers are out of spec by a thou or two, not 10 at the web. I've seen this a lot from good shooting barrels that had excessive runout due to one of 3 things:
1) a poorly dialed in bore
2) a rigid holder that wasn't running coaxially to the spindle bore
3) a floating holder that was not floating... you'd be surprised at just how much this happens.
I’ve actually had the opposite issue with them on two reamers. Both were undersized at the base by a few thousandths. Would just barely work with domestic brass, but no chance with lapua. .008 on the fat side is a lot though.