[I know what automatic fire sounds like - and that wasn’t full auto. 15 months in Vietnam and lots of “meeting engagements” with 40 of us, fighting more than 40 of them.]
I was an artillery scout observer back then and I would get the grid and direction to the enemy in seconds and have 105mm artillery on them in 2-3 minutes.
CAS took slightly longer but if you had a stack waiting out there, we A4s and F4s inbound very quickly.
We had things quite refined when it came to locating and crushing the enemy if they were dumb enough to stick around.