Sorry about the mistake about the listing - comes from looking at TOO many military rifle forums!
If a Springfield 1903 and not a Rock Island, The rifle probably started out as a Rod Bayonet M1903. M1903/05 in 30-03. The rifle may have been converted to a M1903/05 - The M1903/05 outwardly looked like a regular M1903 except for the caliber - or been converted to a .30-06 in the 1907-1910 era. When the .30-06 was adopted, the original barrels had to be modified and many received new barrels. There is a possibility that the 1909 barrel may be original back to when the rifle was modified to 30-06.
Two books you might want to read - both excellent:
1) C.S. Ferris' "Rock Island Rifle Model 1903." Scott A. Duff Publications: Export [PA], 2001
2) Ferris, C.S. and Beard, John. "Springfield Model 1903: Service Rifle Production and Alteration, 1905-1910"
The first book is available through Scott Duff Publications online and other sources. The second book is out of print but is still available through online used book sources.