Man... that is one chattered looking chamber. I say "looking" because it may be dimensionally sound and just appear tool chattered. If on the other hand it is dimensionally out of spec, with the "dark lines" being the areas of under spec....
As the gun is new and under warranty, conjecture is irrelevant. Call or e-mail Colt. Show them the photos and tell them your story. Let them sort it out.
Shoulder Drive Nicholson Club