I have an upper marked with a "C" and an "H". They are not next to each like in word, there is about a 1/4 inch space and the "H" is slightly turned on its axis.
The "C" & "H" are on the right side of the upper receiver just below the A1 sights.
ETA: There are no markings on the barrel itself.
Any thoughts on who the manufacturer is ?
(Sorry, I don't have time for pics, got to get back into court )