The barrel is dated 1956 (at least I think that's a date) and it is interesting that they would still use the M47 designation that long after the war... although not unlikely that Cold War concerns kept them in use. Would 1956 be the date of manufacture or the date of installation? It is a 5-groove barrel with a forged knox, and my 3rd Edition, Revised book by Charles Stratton identifies that as a First Variation. Would they still be making those in 1956? The viewpoint of the base or field armourer is interesting and understandable. I guess I'm fascinated by the relative ease of interchangeability of parts, with this rifle fitted out by manufacturers in Englandicon, Canadaicon, and the USAicon.