M1 Garand - Proof Mark or Imagination/Proof Mark Era

As I understand it, the proof mark ("P") for WW2 M1 Garands is usually stamped on the underside of the stock directly behind the trigger guard, the pistol grip area.  the two attached pictures are from that area on m1 garand rebuild that has ww2 receiver and many other ww2 parts.  1967 barrel.  I can't detect circle or square, but the P is very easy to miss if not in right light or angle.   If anyone out there can tell me if this is indeed the proof mark and from the type of proof mark what era was stamped?  Thank you!! (Will also post on US Miliaria Forum)