Help I.D.ing Barrel please

hey there, I recently received a collecting guide for my M1 Garand and after running several of the serial numbers I have a few questions. The biggest being the barrels origin. This was my dad's rifle first and he had received it from a family friend years ago, so I don't have much in the way of background on it. But this is what I do know.

Its an SA with a serial # in the 2,700,000 range (I don't have it in front of me at the moment)

The Op-rod (6535382 SA), Hammer (C46008-7 SA), and trigger housing
(D 28291-9 SA) all seem to indicate the same time period (1944)

It does have a gas cylinder lock screw w/ P and O, indicating a post WWII conversion.

The stock it's self is marked with the DOE eagle and stars, and it has 2 circle proofs and another none circle proof under the pistol grip.

The barrel it's self has only a single punch mark (top dead center, next to the housing) and a single line cut perpendicular to the length of the barrel, where the serial# may be. Could this be some type of aftermarket barrel?

Thanks for any help on this guys. I just got out of the service and would love to start collecting restoring M1's as a hobby.

The op. rod is from the 50's. A correct 1944 gun should not have a DOD stamped stock. Each circle P (proof) that is on your stock indicates the rifle it was attached to (at that time) passed a proof firing. It would seem that this stock has "been around"
Barrels are normally marked in two places: on right side visible with the op. rod back and/or on top under rear hand guard.

Can't help u on the barrel, but the op rod should be D35382-9 SA, hammer -5 SA and not sure but the t/h# should be D28290-12-SA (my info only shows -1 -2 -5,7,8,12,14,16,18,) My eyes are going bad searching for all these ####.
look for books on the M1 Garand and stick to this site and you will do fine.