This is an original Colt barrel for the Model 1911a1 automatic pistol. This was manufactured by Colt, not a WW2 contractor. It's original military issue and was found in a very early 1912 vintage Model 1911 Colt that was likely upgraded at the beginning of the war (probably circa 1941-42) with new WW2 Vintage Colt parts...mag catch, magazine, and barrel. Barrel has an excellent bore with 65-70% original blued finish. Bottom-side is marked "COLT 45 AUTO" and a letter "P" just below it on the lug. See photos. This is correct for a 1911a1 produced from 1937-1945 or SN# 710,000 to the end of production in 1945. See Clawson book.