Gyvel, that's another one I never heard of, and respectfully, these days the clips should be weaker than ever but...this isn't happening
You're probably right; I was just using that as a hypothetical. I've been (thus far) fortunate enough to escape the M1 thumb. When I was in college in the early 60s, we used M1s for drill in ROTC, but I already knew about the "M1 thumb" from my father, who was in the Battle of the Bulge during WWII.
By the time I was on active duty, the swing was on to the M16. (Although we qualified with M1 Carbines at my first U.S. duty station after basic training.)