This is great information guys. From the research I've done so far, my rifle was manufactured in 1929, so it didn't see WWI, but the rebarreling in 1944 suggests that it saw service in WWII.. after looking into the history books a little, the Army was issued M1 Garands with few exceptions during the war. However, the Marine Corps entered the Pacific with largely 1903's accompanying them. What I've read thus far suggests that the Marines were gradually issued M1 Garands as they came available, but the harsh island environment had taken its toll on many of the 1903's that were issued. Therefore many of the rifles were given new barrels around the close of the war.
Also, from what I understand, the 1903 was issued solely as a sniper variant after WWII to a very few units during the Korean War and early on in the Vietnam War. Those rifles were outfitted with scopes and the sights were removed.
If anyone knows more about this, I'd love to know more. This is just what I've gathered thus far, but if any of it is incorrect, feel free to correct me. This rifle really has a fascinating history.
Marine, NRA member, SAF Defender's Club member, and constitutionally protected keeper and bearer of firearms