Some pre-64 M-70's were stamped. " 375 MAGNUM " instead of 375 H & H MAGNUM there is a photo of one in the model 70 book.

This was re chambered to 375 AI.

Are the shoulder angles on all AI calibers the same?

I believe so, I think they are 40 degrees

Mills

If it’s Ackley & looks like it , I have his books, can copy the sections for you

William

William, If you're referring to Ackley's HANDBOOK for Shooters and Reloaders, I posted his comments and data. See post #12

Reloading data for this is a moot point as Mills doesn't reload.

My early 25" straight taper .375 H&H Super Grade has "375 Magnum" stamped on the barrel. Could this #10150 be a first year gun? I'm not enough of a Model 70 guy to own Rule's book.

I appreciate all of the advice and honest opinions here. Long story short, the 375 is going down the road and at least one 30 06 is taking its place.

Bill your gun was made in 1937.