I was in a Huey company in Vietnam and pilots competed for coolness with the weapons we took along.
There were M1A1 Thompsons, M3 grease guns, folding AK’s, M1A1 carbines, and the ultimate in cool, the Carl Gustaf or `Swedish K’. CAR-15’s turned up as well.
The grunts we carried made do with M-16’s. We pitied anyone we saw humping an M-60 or a baseplate.
At various times I carried a Thompson, CAR15, M79 blooper, M14, and M3 grease gun and of course an M16. I have to think as I may have missed one or two.
I was always looking for a good brush-chopper. The .45 cals excelled in the role but were just too damned heavy even if you only carried a hundred rounds. I used to see trace round from the 5.56mm’s bounce off of and be deflected by the undergrowth.
I finally got an M14 and hallelujah!