RIA 1903 S/N 398186 with SA 1918 Barrel

[jjspearson]

I recently purchased a RIA 1903 with receiver number of 398186. I understand that this serial number is after RIA stopped making completed rifles. From other posts, I think it is likely that this receiver was shipped to SA to complete the rifle. I am wondering if the 1918 SA barrel was the original barrel with this rifle? Lyman 48S sight apparently was added post WW II.