"My weapon was overheating," McKaig said, according to Cubbison's report. "I had shot about 12 magazines by this point already and it had only been about a half hour or so into the fight. I couldn't charge my weapon and put another round in because it was too hot, so I got mad and threw my weapon down."360 rounds in 30 minutes through your rifle and your gun became unreliable? Wow I would have never guessed that if you overheat a machine, it becomes unreliable or breaks. Ditto the other soldier who ran 600 rounds through his M249. If you want to avoid overheating, you can change out the barrels on machine guns for a reason.
More telling for me is the opener of the piece:
In the chaos of an early morning assault on a remote U.S. outpost in eastern Afghanistan, Staff Sgt. Erich Phillips' M4 carbine quit firing as militant forces surrounded the base. The machine gun he grabbed after tossing the rifle aside didn't work either.If someone is trying multiple types of weapons and none of them work, that isn't a criticism of the weapon. If none of the guns work, the only systematic element they all have in common is the soldiers tasked with maintaining them. And there is no magic rifle design that won't fail without proper maintenance.
This isn't to say that everything is hunky dory with US small arms. The SAW in particular is not a very good gun, something the newer lightweight versions of the weapon only make worse. But the M4 is, by all accounts, a decent weapon.