Thanks for listing this here. There are a few members here who really like the NM Winchester model 70's. I do believe ALL National Match rifles had the clip slot. I'm looking for the exact quote by Roger Rule in his "the rifleman's rifle" book. Your rifle also looks like it's never had a lyman or other aperature sight installed. the front sight ramp looks like an original NM. Is the barrel drilled/tapped for the telescope sight block? It appears to have the #5 marksman stock which would coincide with the year of manufacture of your rifle. Do you know if the trigger has a "T" stamp on it?
Edit to add: Taken from Rules "The rifleman's rifle" book:
Page 181
According to Rule: "All National Matches were slotted for loading with a clip, regardless of the era or production period"....
