The M1A shown in that post shoots the .308 Win/7.62 NATO, only a shade less powerful than the 30-06 the GIs carried in Korea. Never heard any complaints about the M1 stopping anyone.
“You may want to check with your friend and ensure he was not talking about the M1 carbine, which is/was a notorious pipsqueak.”
Ah! That resolves it. Yes, he was talking about the M1 carbine, from personal experience. He said his unit was being charged by a ChiCom wave, and he was shooting at a large soldier. He knew he was hitting because he could see puffs of dust and filling from the quilted jacket, but the guy kept coming. His CO put the man down with a .45 cal. The man has passed away now, but I remember it was most definitely the M1 carbine. I used to hang on his narratives.
My fail for not identifying the weapon in the image correctly.