Key word there “rarely” still happen. I like the AK and the AR. But picky when it comes to the AK.
Personally, I cannot find a single documented case of it ever happening, outside of the specific instances that I listed. I can’t prove it didn’t happen, just as folks cannot prove that it did happen, so I used the phrase “rarely”.
When I was a young Marine, our senior officers and SNCO’s were all Vietnam vets, as well as several friends and family members of mine. This is a conversation that I’ve had before.
Your statement makes it sound like this was a common practice, when it was not. Additionally, you cannot compare the reliability of the 1960’s M16 platform and ammo with the modern variants and ammo. The ammo was part of the problem. Feed any weapon crap ammo and you get crap performance.