This is coolbert:
Here with an extract from that report comparing the advantages of the AR-15 rifle as issued to American and South Vietnamese [VN] troops for field trials during that most early stage of the Second Indo-China War.
"Weekly DTIC: The AR-15 In Vietnam, 1962"
"Analysis: Based on the numerical ratings and the comments of US Advisors and VN Unit Commanders, the AR-15 is the most desirable weapon for use in Vietnam for the following reasons: 1. Ease of training. 2. Suitable physical characteristics. 3. It is easy to maintain. 4. It is more rugged and durable than present weapons. 5. It imposes the least logistical burden. 6. It is the best weapon for all-around tactical employment. 7. Its semi-automatic firing accuracy is comparable to that of the M1 Rifle, while its automatic firing accuracy is considered superior to that of the Browning Automatic Rifle. 8. Vietnamese troops, Commanders and US Advisors prefer it to any other weapon presently being used in Vietnam."
Within the context of the Vietnam War the AR-15 [became the M-16] superior to any other weapon.
That close quarter combat as experienced in Vietnam made the M-16 the American weapon of choice.
About half [50 %] of those firefights as occurred in Vietnam at a distance of twenty meters or less!
This particular evaluation only considering the accuracy and penetrating power of the AR-15 round in contrast to that of the M2 carbine.
That M2 carbine originally the M1 from the era of the Second World War. The M2 having a larger magazine capacity and also automatic capable on demand!
"Selective fire (capable of fully automatic fire), 30-round magazine"
A troop in Vietnam subsequent to the adoption of the M-16 as the standard American battle rifle [replacing the much heavier M-14] ABLE TO CARRY TWICE THE AMOUNT OF AMMUNITION FOR THE SAME WEIGHT! But that was for the future!
That attribute of the AR-15 in both selective fire modes at least as good as or superior to the M1 rifle and the BAR. That also had to be considered as a plus.