There are some things about the rifle that seem a little off. As Pickax said, the Marines only applied the punch mark in front of the serial for a very short time in their rebuild program. The punch mark signified that the receiver had passed the Rockwell hardness test. But the thing is the same time they were applying the punch mark, they were also drilling the additional gas escape hole, which I call the Borden Hole to try to give credit to the correct man. So to not have that additional gas escape hole is sort of a red flag.
Also as pickax said someone else at one time was also applying that punch mark. For instance the Mariens only applied the punch mark in 1938, and possibly early 39. But you see M1917's and 03A3's with them as well. The Marines didn't have any M1917's after 1920 and the 03A3 I can only trace a few they received after WWII. So there are for sure rifles out there with the punch mark that were not applied by the Marines. If there are M1917's and 03A3's like this, there have to be M1903's as well that weren't Marine done.
The barrel is also sort of a red flag. In Feb 1943, the Marines stated that their surplus of M1's had finally caught up and they no longer needed their M1903's, so they started to give them away. This included all the spare parts they had for the M1903 as well. Basically the way the docs read, the Marines seem to be done with rebuilding M1903's after Feb 1943. You see the greater part of 1943 with the Marines communicating with anyone to take the rifles and parts. The Marines gave away for free over 5000 loose barrels to the Navy, which by the way the docs read, I think were mostly all the 43 and 44 Sedgley barrels. The Navy received these in 1944 at a time the Navy as well was winding down the M1903 program and it's unclear if they would have used much of these spare parts or not. Not much is known about the two Navy Rebuild depots that rebuilt M1903's. But I do see later in the docs that the Navy turned over a lot of their parts and rifles to the Army at Wars end when they adopted the M1 in 1945.
I hate to say it but it's more likely your rifle was built by someone other than the Marine Corps. I'm very sorry to say that.![]()