1. Rock Island made spare barrels but only for M1917s in WWII - such barrels were marked with a RIA but no month/date.
2. Remington made spare M1903A3 barrels through much of 1944, but no M1903 barrels.
Due to the relative availability and cheapness of RA 03A3 barrels, it was fairly common to see them modified slightly and used on M1903s by civilian (not military) owners.
I'm almost positive your son saw a Remington barrel, unless Bubba tried to modify it.
"We make men without chests and expect from them virtue and enterprise. We laugh at honor and are shocked to find traitors in our midst."
--C.S. Lewis