As often happens when a smith places a factory barrel on a rifle action, he possibly indexed the barre so that the original factory stampings are on the under side of the barrel and are hidden by the stock.
You might have to remove the stock to see the original factory markings.
No factory Rem 600, 660, or Mohawk came from the factory with a bull barrel that would be .750" at the muzzle. They all had sporter weight barrels even though, IIRC, the Mohawk was a fairly heavy sporter contour.