With all due respect, the argument rings hollow. It does not seem to be credible, whatsoever.

I could believe that during the years from 1930-40 that John Garandicon may have experimented and changed metallurgy for failing components, based upon user experience and wear patterns.

I find it simply beyond the pale that Winchester had any lattitude at all in deciding what sort of metal to use, other than what was mandated. They changed nothing unless paid.

To suggest that they did what they wanted seems to be contradictory and without foundation or support from SA.

Anecdotally, gunsmiths like G fisher would have noted some sort of pattern over the years with those CM marked items; that has not shown to be true.
I suspect that in fact there is no deviation at all in metallurgy between CM, A, and punchmarked and SA items.

Only a test of all types of bullet guides, clip latches, trigger housings etc of all of them would show such a claim to be true.
That has not been done.

In any sort of scientific method there is a way to prove things and "one" does not make a trend or a truth.

The list of metals used is available in any of the above mentioned books.

Do you have a link?