Military firearms...
...procurement is limited in two areas:
- Faster, better, cheaper. Choose two.
- Project management - Triple constraints - Time, money, scope.
The M60, as kraigwy points out, is a fine weapon. The designers based things on the MG42, which is the direction modern weaponry was taking.
The M1, while on the cutting edge of 1930's technology, could have been much better. It could have been chambered in .276 Petersen (D. MacArthur nixed the caliber), and it could have been built with a removable magazine instead of an en bloc clip. However, it was still superiior to everything out there at the time.
The M1 Garand was also a peace time development. There was no war on the horizon, so its development was was not pressured by combat needs. World War II ramp-up of production caused it to be outsourced to Winchester and International Harvester.
The British Bren was a licensed copy of a Czech design. Probably one of the superior designs of the era; much superior to the Browning BAR.
While the M14 was, by extension, a modernized M1, it was probably somewhat inferior to the FN/FAL. The M14 was superior as far as long range use, but the world of combat had moved from long-range engagement, to that of close-in combat. The FN/FAL is a great rifle. However, its procurement couldn't be guaranteed if the USSR overran Europe. There was also tremendous pressure to stay with Springfield Armory. Homegrown and bred.
The M16 came with its own problems. Most of which were caused by the "gee whiz" factor of the U.S. Department of Defense procurement. Juicing up the powder to decrease cycle time, lack of education for the end user, and poor maintenance, all nearly spelled disaster in Vietnam. However, the M16 uses the same basic design. Forty-odd years is an eternity in firearms life. So, that speaks to the strength of the design.
Now, with the need for longer-range engagement, the M14 has come back into favor. Nothing says hello like a M80 ball cartridge at 800 yards.
For over 160 years, the Springfield Armory produced the military's firearms, contracting out during times of war. By the 1960's, Robert McNamara decided to outsource small arms, and eliminate the government-owned monopoly on military firearms. Armalite, then Colt, got the business. Were troops better off? From strictly a technology basis, yes. The M16 platform was light years away from the M14. Was it properly handled? Unfortunately, no.
There's an outstanding book available which discusses what won World War II. "
Why The Allies Won", by Richard Overy, is a great analysis of how the war was won.