Trying to settle a bet: Finish is inconsistent, coarse to the touch and the blackened areas are not carbon. What do you guys think?

Not sure looks media blasted hard to tell

Agree it looks media blasted or maybe harsh chemical? But, I don't think it's a Colt based on the asymmetry of the ejection port side lobe of the "T."

Really looks like someone took it to a grinding wheel, then sprayed it with Norrels.

Not sure, but we need to see all the places where tool marks might be.  We can partially see the deburr marks on the ejection port side of the "T", we need to see the right side of the "T" and the back of the "T" for GM type marks.  There are tool marks across the top of the "T" that I don't remember seeing before.  Some (older?) charging handles have been milled across the top of the "T" and you will see circular tool marks but I don't recall seeing the horizontal tool marks on this one.  Rough black finish might mean refinished.  (Look at the tacked GM thread for examples of GM style tool marks)  I've posted pics of other charging handle details but can't remember where... :)