I have no combat experience but I do talk guns with vets at my local Rod and Gun club. The Vietnam vets I shoot trap with say they wanted something with more punch but the younger Iraq/Afghanistan guys seem to like their M4’s.
Me either. My Dad earned his Expert Infantry badge, as well as the CIB, two years in VN.
Not long after the initial problems with the M16 (the shape of the powder grains?) some in the field were having, I asked him what he thought of it.
He really liked it and said it worked fine “if you kept it clean.”
I finally got an M4, a `CORE’ made by veterans. Very nice. A lot different from my commie tommie.