Now that you mention it, the "1" on the receiver and barrel SN does appear to be hammered in there pretty deep. But how would a rifle like this come to be? You say it's rebarreled: does that mean someone bought an unused No.1 barrel from government surplus, and put it on this receiver, then stamped them both to match, and put new (old) Slaz wood on it?
Also, I read somewhere that the nose cap sn wasn't always applied on some arsenal refurbs. Opinion?

I'd be more inclined to agree with the sporter refurb suggestion if the barrel and bolt head weren't in such good condition.