My old buddy Lester H. Hawkes, formerly of Kalispel Montana had a matched pair of 1952 M70's, both with 2 1/2X Lyman Alaskans right from the factory, seems to me.
He used one for guiding, which he cut to 22" of barrel. The other was stock & as of 1976, was unfired. I was the first one to shoot it & with his old load of 70gr. 4064 and a 270gr. Winchester Power Point. I see this load is now 2gr. over max according to Hodgdon. 70gr. was the GO-TO load for .375's and 270,s back in the 70's and 80's. 68.0gr. was the 300gr. load.
Interesting, this "progress". No - those loads were not excessive. I used the same loads in my BRNO .375. NP- ever.
A buddy of mine in Smithers owns that 'barely fired' 1952 25" bl'd, M70 .375 today.
The other one disappeared to Hyder, Alaska, with his step - kids I assume, after he passed.