PS: He also writes in On Killing that approx 50,000 rounds were expended for EKIA(enemy killed) in the entire SE Asia conflict
Apples and oranges.
I didn't count the shots, but I don't dispute it. It had nothing to do with marksmanship.
In most firefights you never say the enemy. It was one side hidden in a wood line shooting at another side hidden in their wood line.
This was about firepower, not marksmanship.