McNamara was a Ford executive prior to being made Secretary of Defense. He and his gang of
Whiz kids found the management practices of the Department of Defense as Byzantine, illogical, chaotic. And DoD was that and more. One good reform was assigning a Project Manager, a single point of contact, to push a program through to fielding. This was needed as the prior Ordnance Department practice was more or less to play hot potato with a program. All of these men followed the Harvard Business Management philosophy that you did not need to know or understand the product to be a manager of that product. That is managing potato chips is the same as managing computer chips, as chips are chips. These sort of managers are good at optimizing processes, reducing costs, but they are not innovative and tend to be same old, same old when it comes to product lines.
It is too much to expect Robert McNamara to be a small arms specialist. It is, in fact unfair. He had a war going on, lots of planes, tanks, ships, etc under contract and in development. Neither was the Army fully in agreement as to what a service rifle ought to be. From the 18th century past WW2 the Army believed in the gravel belly soldier. That is the expert shot, who with his rifle, controlled a 1000 yard battle radius around his position. It was a dream, clearly shattered by the artillery of WW1, but totally adhered to between WW1 and WW2, and still very influential till the 1950's when it began being questioned.
It was the total fault of the Army not to have put money into rifle development post WW2. I recall reading the whole rifle development budget was around $1,000,000. Which would have not met the fuel bill for a month for an Armored Division or an Air Squadron (a guess, but would be true today!) This parsimony is totally the fault of the entire chain of command of the Army, going right to the Army Chief of Staff. Instead of fully fleshing out intermediate round concepts, intermediate round rifles, the Infantry School decided it still needed 30-06 power and range, and with a tiny budget, the Ordnance Department simply product improved the Garand. The Infantry school was so retrogressive, it did not want detectable magazines! It wanted to keep stripper clips. There exists in one book the Infantry School position on box magazines: they are too heavy, they are too expensive, there is nothing good about them. This is the reason in early literature the box magazine on the M14 is called "semi detachable" and why there is a stripper clip slot on top of the receiver. The shooter was to fill the magazine with five round clips, on the rifle. When the rifle was introduced at the National Matches, competitors were told to reload the rapid fire stages with stripper clips! I tried that once, what a malfunction creating nail buster. But it shows just how neolithic the Infantry School was, and is. Yes, Robert McNamara had to force a new rifle down the throats of the Army, because the organization is incapable of self reform.But, he should not have been put into that position. And this is what you get when some manager in a cubicle of the Pentagon has to make an instant call as to what boot the troops should wear. The decision maker is so far removed from the problem, he is out of touch with the realities on the ground.
As much as I loved my M1a, it was not the rifle we should have adopted. The British were on the right track, the Infantry School should have listened to the British, and they should have really looked at the German SIG 44, the SKS, AK47, all of which showed the way to the future. But the Infantry likes what it has, wants something better, but only a little different, and totally rejects revolutionary change. The post WW1 Ordnance Bureau assigned too much weight to the knuckle draggers hopes and desires. The pre WW1 Ordnance Bureau understood, as far back as time itself, that the user was hidebound and moving mountains was easier than changing infantry school opinions. It is certain that pointy sticks had to be wrestled from the grasp of Troglodyte Infantry before they would hold flint tipped spears. And even then, retired Troglodyte Warrant Officers loudly told anyone, that the flint tipped spears were never as good as the old pointy sticks. It is just the way these guys are.