Between December 1, 1958 and March 22, 1959, the ranges at the Hunter Liggett Military Reservation were the scene of an impressively comprehensive set of trials. The Army wanted to know what effect the new lightweight, high velocity rifles would have on squad organization and hit capabilities. So, they arranged four months of testing with squads of 5, 7, 9, and 11 men armed with M14 rifles, the new Armalite AR-15 rifles, and the Winchester Light Military Rifle. These squads conducted a carefully planned mixture of daytime offensive drills, daytime defensive drills, and nighttime defensive drills, while using specific fire modes (semiauto, fullauto, and specified combinations of the two).
The basic conclusion of this extended testing was that given combat loads of equal weight, 5 to 7 men with lightweight rifles had the combat effectiveness of 11 men with M14s. In addition, it was advised that the Winchester needed to be more durable and was equal in hit probability to the M14. The AR was found to need better sights, and to be equal in reliability to the M14 (remember, this is before the ball powder debacle in Vietnam). Full-auto bursts of 3-6 rounds were found to be effective and useful in both of the lightweight rifles (unlike the M14).
You can read the complete report here: