I did call and talk to one of the guys at Carbon Six/McGowen about their barrels. He said they are crazy busy and a majority of the barrels they make are carbon wrapped. He said they guarantee 0.5 moa accuracy and will replace the barrel if it doesn't produce.....they want you to be happy with their product
I have one I built for a friend on a Stiller action chambered in 300 Win mag. I was against the carbon fiber route at first but he wanted one. Very pleased, shooting sub 1/2" groups with 200 accubonds and 1/4" groups with Sciroccos. Courteous and pleasant folks to deal with, I'm not surprised they're busy. Will likely take 3 months but worth the wait I think.