Not that I like Rumsfeldt, but up to a point he was right, you go to war with what you have, not what you like.
Where he failed (miserably as all of his ilk do) is that once we see its not working, the American Public wants them to do their damndest to correct it.
The K31 would have been fine in WWII, it certainly vastly exceeded the MN, and was better than the Mausers and the Japanese rifles.
If I was a grunt I would be happy for a tactical Nuke over an M4. That really solves the problem of you dying or maimed.
A grunt would beyond belief prefer and M1 Abrahams tank over a Sherman. Kind of so what? They did not have them, Shermans served and served well.
While the K-31 is different, its not quirky.
And an M-16 badly executed (Vietnam with the powder change debacle and cleaning issues) is beyond worse than an M1 that works. It was a junk design that took a lot of lives to correct. Many dyeing with screwed up weapons.
Giving drafted infantry a machine gun is and was a recipes for disaster.
I have corresponded with a grunt out of the Sand pits. His comment is that they almost never use full auto.
I love the comment about if the Germans had invaded Switzerland (and it was very possible as it was a route into France in that corner of German, Switzerland and closely adjacent France)
We would shoot twice and go home.
To compare a K-31 of its era with an M4? hmmm.
Quality wise the 1903s were up there with the K-31. The 1903A3 while still good is not that level. K-31 and 1903 were hand built, the 1903A3 mass produced (and rightfully so as was the M1 - weapons in your hands is vastly more important than a higher but not needed quality)
Russia went back to the MN from the SVT-40 for the same reason. They needed guns, you could mass produce the MN, not nearly so the SVT