Ben you have missed the point altogether. The seller presented the rifle as an original as converted M1D. Though authorized in September 1944 as a substitute standard for the M1C, to my knowledge no M1Ds, other than trial models, were produced during WWII. Incidentally Duff agrees. I have never seen or documented a papered M1D with a barrel date earlier than mid-1951. Most are 1952. So the point is, the receiver was manufactured 1944 and if indeed as converted, the M1D in question would most certainly have had the "later" sights installed, would have a barrel, with unique part number, dated post mid-1951 and various other "characteristics" I won't go into. Any discussion about the original configuration of the receiver, as manufactured in 1944, is moot if indeed the rifle in question is an "original as converted M1D".