Non-Milsurp: Winchester M70 Identification Help WHAT IT BE!

[vintage hunter]

Everybody and his brother did something to M70's at one time or another. A heavy barreled .308 isn't exactly unusual.
That one looks like a Heavy Varmint Rifle. Like this one.
Winchester Model 70 SA Heavy Varmint .308 Win.

What does a 308 have to do with this thread? The OP'srifle is a .243. But since you brought it up...
Factory made pre-64 Winchester model 70 heavy barrel varmint/target rifles in 308 are very unusual because they're virtually nonexistant.
Factory post 64 model 70 varmints(OP's rifle) in 308 made under Olin ownership(1964-1980/81)are not common, but they are around. Oddly enough every one I've seen so far bore electro penciled u.s. property markings on the reciever ring.
Model 70 heavy barrel 308's made by USRAC from '80 or '81 until 2005? and those made by FN HERSTAL in Columbia. S.C. from 2007?-present are a dime a dozen and, IMO, should'nt even be allowed to bear the Winchester name.