Picked up a 051xxx National Match SAI rifle (confirmed as such by SAI, 11/14/89 manufacture) this past week. It has a standard weight NM barrel on it. The newer NM rifles from SAI come with a medium weight NM barrel, the same weight as comes on a loaded. My question is at what serial number range did SAI switch over to a medium weight barrel? Anybody know? Was it at the same time as the loaded came out which I'm pretty sure was 1996/1997?