Greetings. I recently picked up a Remington 1903 at a gun show. Inspection shows it to be a mix-master of parts. The SN is 3357*** which according to the info that I can find puts it at a Dec '42 manufacturing date. However, the barrel is dated Feb '43. I know that this was during the period when Remington was moving from 03 production to 03A3 production. My question is would a Feb '43 barrel have been installed on a Dec '42 receiver, or is this mostly likely a rebuild?