WASHINGTON -- In the chaos of an early morning assault on a remote U.S. outpost in Afghanistan, Staff Sgt. Erich Phillips' M4 carbine quit firing as militant forces surrounded the base. The machine gun he grabbed after tossing aside the rifle didn't work either.
When the battle in the small village of Wanat ended, nine U.S. soldiers lay dead and 27 wounded. A detailed study of the attack by a military historian found weapons failed repeatedly at a "critical moment" during the July 13, 2008, firefight, putting the outnumbered Americans at risk of being overrun.
That raises the question: Do U.S. armed forces have the best guns money can buy?
Despite the military's insistence that they do, a small but vocal number of troops in Afghanistan and Iraq has complained that the standard-issue M4 rifles need too much maintenance and jam at the worst possible times.
Early this month, eight U.S. troops were killed at a base near Kamdesh, a town near Wanat. There's no immediate evidence of weapons failures, but the circumstances were similar to Wanat: Insurgents stormed an isolated U.S. base.
Army Col. Wayne Shanks, a military spokesman in Afghanistan, said a review of the battle at Kamdesh is under way, but "it is too early to make any assumptions regarding what did or didn't work correctly."
Complaints about the weapons, especially the M4, aren't new. Army officials say that when properly cleaned and maintained, the M4 can pump out more than 3,000 rounds before any failures occur.
The M4 is a shorter, lighter version of the M16, first used in Vietnam. About 500,000 M4s are in service, making it the rifle troops on the front lines trust with their lives.
Sen. Tom Coburn, R-Okla., a leading critic of the M4, said the Army needs to move quickly to acquire a combat rifle suited for the extreme conditions U.S. troops are fighting in.
U.S. special forces, with their own acquisition budget and the latitude to buy gear the rest of the military can't, are replacing their M4s with a new rifle.
"The M4 has served us well but it's not as good as it needs to be," Coburn said.
Battlefield surveys show nearly 90 percent of soldiers are satisfied with their M4s, said Brig. Gen. Peter Fuller, head of the Army office that buys soldier gear. Still, the rifle is continually being improved to make it even more reliable and lethal.
Fuller said he's received no official reports of flawed weapons performance at Wanat.
"Until it showed up in the news, I was surprised to hear about all this," he said.
The study by Douglas Cubbison of the Army Combat Studies Institute at Fort Leavenworth, Kan., hasn't been publicly released, but copies have been leaked to the media and are circulating on the Internet.
Cubbison's study is based on extensive interviews with Phillips and other soldiers who survived Wanat. He describes a well-coordinated attack by a highly skilled enemy that unleashed a withering barrage with AK-47 automatic rifles and rocket-propelled grenades.
The soldiers said their weapons were meticulously cared for. But still the weapons had breakdowns, especially when the rifles were on full automatic, which allows hundreds of bullets to be fired a minute.
The platoon-sized unit of U.S. soldiers and about two dozen Afghan troops was shooting back with such intensity the barrels on their guns turned white hot. The high rate of fire appears to have put a number of weapons out of commission even though the guns are tested and built to operate in extreme conditions.
Spc. Chris McKaig was firing half a dozen rounds at a time at insurgents from a M4 but soon developed problems with his M4, which carries a 30-round magazine.
"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."
Soldiers also had trouble with M-249 machine guns, which can shoot up to 750 rounds a minute.
Cpl. Jason Bogar fired about 600 rounds from his M-249 before it overheated and jammed. He was killed during the firefight, but no one saw how, the report said.