SDH:
1254780 does not fit into a block of NRA Sporters, and the front of the receiver does not appear to be rounded, so I don't think it's a factory Sporter.
The star gauge and the barrel date have no particular correlation, all star gauged barrels were star gauge marked after a certain date, which escapes me right now........your star gauge mark should look like a "turtle"., a circle with six lines radiating out at 6 o'clock on the muzzle.
The front sight elevator block is original 03 Springfield, the blade is an aftermarket replacement.
I have absolutely no clue what the 187475 over 80 means, it wasn't put there by Springfield Armory, at least I've never seen that before.
Are there some star gauge markings about 1/3 of the way up the barrel from the receiver? They would consist of a letter and 2 or 3 numbers, like an A over 123, those would be the star gauge numbers on the star gauge sheet that came with the barrel. There also should be a proof P around there somewhere. Star gauge letters and numbers were on the bottom of Sporter barrels, and the top of National Match barrels.
One caveat, most people don't know, but replacement NRA Sporter barrels didn't have the star on the muzzle, at least not on the ones I have seen. They do have the star gauge numbers on them.
HTH
