Just checked my 1982 M.70 FTW and it measures .277". The longest free bore I've seen is on my CZ-550 7x64 yet that hasn't hurt it at all in the accuracy department.
Shew me thy ways, O LORD: teach me thy paths. "there are few better cartridges on Earth than the 7 x 57mm Mauser" "the .30 Springfield is light, accurate, penetrating, and has surprising stopping power"