I have a 03A3 Mark I that has been with me for over 50 years. I would say it is 90 to 95%. Barrel date is 8-18.
If you have a barrel dated 8-18 (August 1918) , the rifle cannot be an original 03A3. See next:
'The U.S. Model 1903 Springfield Rifle replaced the Krag-Jorgensen and was the primary U.S. battle rifle until 1936, when it was replace as the primary battle U.S. battle rifle by the M1 Garand. In 1942 Remington Arms redesigned the 1903 rifle using some stamped parts and designated it the U.S. Model 1903A3.
There is a great lineage of 1903 models that were manufactured from the introduction of the 1903 to the development of the 03A3 rifles, *including but not limited to:
* M1903 Rod Bayonet Rifle;
* WWI 1903 Rifle;
* M1903 Mark 1 Rifle;
* M1903A1 Rifle;
* Remington M1903 Modified Rifle;
* Remington M1903A3 Rifle;
* Smith-Corona M1903A3 Rifle.'
ps - was writing at the same time as post above. sorry for duplication.