I recently acquired this CMP Springfield that has a serial number indicating it was produced in March, 1945:
The date stamping on the barrel, 1 S A 2 45, would indicate it was made in Feburary, 1945, and is probably original to the receiver:
https://www.milsurps.com/images/impo..._zpsedc5-1.jpg
Bolt
https://www.milsurps.com/images/impo...sf0650bb-1.jpg
Other marked parts found upon field stripping the rifle are also SA stamped:
Operating Rod
https://www.milsurps.com/images/impo...kings_zp-1.jpg
Trigger Group
https://www.milsurps.com/images/impo...kings_zp-1.jpg
The receiver leg has an electro-pencil mark LEAD over 1.65 indicating that the rifle underwent a rebuild at Letterkenny Army Depot in 1965:
The stock has the circled P proof stamp behind the trigger guard and a very faint partial cartouche with SA over an O on the left side of the buttstock:
I found a discussion on another forum that suggested M-1s with the electro-penciled Army Depot rebuild dates may have come directly to CMP from the former DCM inventory of overhauled rifles.
I would deeply appreciate any questions, corrections or additions to the information I have regarding the history of this firearm based on the data I have gathered so far.