This is a .300 H&H Magnum standard contour barrel from a Model 70 rifle. The manufacturing date falls somewhere between 1957-1963, determined by the 18-line #7 sight ramp (model 70 barrels were no longer stamped with a manufacture date after 1956).
Bluing - 90% - The bluing is dark and even.
Metal - This barrel has numerous scratches, but no deep dings or other significant marks of metal damage.
Bore - 7/10 - The bore has light wear in the throat and pitting in the last inch near the muzzle. Borescope verified.
We use the NRA Modern Gun Condition Standards Grading System for grading part conditions. You can read about it HERE