.
It might help to know why you're asking.
Have you seen one?
Do you have one?
Are you looking for one?
To my knowledge, except for the 40X rifles, they didn't make any (factory) M700s with heavy/varmint-weight barrels ("Varmint Special") until the late 60s (1967).......and then they were mainly chambered for varmint calibers (.22s & .24s) until sometime in the early 1970s when they started chambering them for the .308 and .25-06 (the only long-action chambering for the Varmint Special rifle).
If you have one or have seen one, you would want to inspect the barrel for the "Remington" logo and date stamp information. If that information is not present, it would have been one that was re-barreled.
By the way, the M700 wasn't introduced until 1962.
Den