Springfield M-1 Garand

I know very little about Garands, so I had a knowledgeable friend look this rifle over and he told me the following: the S/N is 5,850,558 which is a 1955 production date. The barrel is a Springfield with a mark of 4-1955 so it matches the action. There is a proof mark "circled P" from Springfield. There is a cartouche of "3-stars over an eagle" which is from the CMP. The sling looks like a date of 1958. The photo of the card is an independent grading that came with the rifle. Best plan of action is to take a look at it.