XM177E2 “Colt Commando” Carbine (Model 629)

A Jungle-Born Weapon of War

The Jungle War That Demanded a New Weapon

The Vietnam War was unlike anything the American military had fought before. Thick triple-canopy jungles swallowed entire platoons, the air was hot and choking with humidity, and ambush could come from any direction. Soldiers carried the new M16 rifle, touted as revolutionary—a light, accurate rifle firing high-velocity 5.56mm rounds. On paper, it was a marvel of modern engineering.

But in practice, the long 20-inch barrel of the early M16 proved awkward in the tight, tangled vegetation of Vietnam. Patrols moved slowly. Quick reaction, essential when ambushed by Viet Cong or North Vietnamese Army troops, was hindered by the rifle’s length and weight. Special Forces and elite units, tasked with moving fast and hitting hard in some of the most dangerous corners of the war, demanded something else.

From this need for speed and maneuverability, the idea of a compact carbine was born. The first attempt was the XM177E1—a weapon that promised agility but brought with it new problems.

The First Attempt: The XM177E1

The XM177E1 was Colt’s initial answer to the cries for a shorter rifle. With a 10-inch barrel and collapsible stock, it looked like the perfect weapon for the jungles of Southeast Asia. It was light, compact, and easy to handle. Troops could swing it around in thick brush or use it comfortably when exiting helicopters in a hot landing zone.

But once the weapon met combat, its flaws became glaring. Each shot produced a fireball at the muzzle, lighting up the jungle night and revealing the shooter’s position. The thunderous blast was deafening, even for seasoned soldiers, and the shortened gas system made the rifle prone to malfunctions. Extraction failures and jams left soldiers in deadly situations without a working weapon.

For elite units who could afford no failure in the field, the XM177E1 was a compromise. It gave them mobility, but at a steep cost in reliability. Something had to change.

Evolution Through Fire: The XM177E2

From the lessons of the E1, Colt engineers refined their design. The barrel was lengthened slightly to 11.5 inches, giving the weapon more reliable ballistics and improved functioning of the gas system. A distinctive feature was added: the large, cylindrical muzzle device known as the moderator. Though it did not fully suppress the weapon, it reduced muzzle flash and tempered the violent blast that plagued the E1. Soldiers described the sound of the weapon as unforgettable—like the crack of crushing a banana.

The XM177E2 was still compact, still aggressive, but now it was a weapon soldiers trusted. The collapsible stock allowed it to be carried tight to the chest, ready for action in dense terrain or aboard helicopters. Its light weight meant soldiers could carry it alongside heavy loads of ammunition and gear without being bogged down.

For the men of MACV-SOG, the Navy SEALs, and the Green Berets, the XM177E2 was more than just a tool of war. It became a symbol—a badge that set them apart from the line infantry. To carry a Colt Commando was to step into the world of clandestine missions, cross-border operations, and the dangerous shadow war fought deep behind enemy lines.

The Warriors Who Carried It

MACV-SOG

Perhaps no unit became more synonymous with the XM177E2 than the Military Assistance Command, Vietnam – Studies and Observations Group (MACV-SOG). These shadow warriors conducted top-secret reconnaissance and sabotage missions across the borders of Laos and Cambodia, often facing overwhelming odds. Speed and silence were their greatest allies, and the XM177E2 gave them both. Compact enough to maneuver in the thick jungle and powerful enough to unleash withering fire when ambushed, the carbine became a lifeline in their hands.

U.S. Navy SEALs

Operating in the deltas and waterways of South Vietnam, Navy SEALs also prized the Commando. Their missions were swift, violent, and unpredictable, often involving nighttime raids on Viet Cong positions. The XM177E2’s compact frame was perfect for fighting in boats, moving through swamps, or clearing bunkers. For SEALs, the weapon’s bark was part of its identity—a reminder that speed and aggression often outweighed stealth in the chaos of a firefight.

Green Berets

For U.S. Army Special Forces, the XM177E2 embodied their mission: to train, fight, and lead unconventional warfare. Whether working with Montagnard tribesmen or carrying out direct action missions, the Commando represented adaptability and the edge that separated elite warriors from the rest.

The Sound of the Commando

One of the most haunting memories veterans carry is the sound of the XM177E2 in battle. The “banana crack” was distinct, unlike the longer M16 or heavier M60 machine gun. Its report carried through the jungle with a sharp violence.

To those who fought with it, the sound became synonymous with survival. For some, it was the reassurance of fire support in the dead of night. For others, it was the desperate last stand in a sudden ambush. The XM177E2’s voice became part of the auditory landscape of the Vietnam War. The Colt Commando was not issued widely across the military. It was carried by the few—the men who went into places others would not, who carried missions of secrecy and sacrifice. In this way, the XM177E2 became more than just steel and plastic; it became a mark of belonging.

Much like the famed Fairbairn-Sykes dagger of WWII commandos, or the Thompson submachine gun of paratroopers, the Commando embodied a spirit of daring. To see it slung across a soldier’s chest was to know he was no ordinary infantryman—he was part of an elite, chosen brotherhood.

Legacy: From the Jungles to the Modern Battlefield

The lessons of the XM177E2 shaped the future of American small arms. The idea of a short, maneuverable carbine with a collapsible stock became the foundation for the M4 Carbine—the weapon that today serves as the standard rifle of the U.S. military.

The DNA of the Commando lives on in every M4 carried across Iraq, Afghanistan, and beyond. The need for mobility, adaptability, and compact firepower, first realized in the crucible of Vietnam, proved timeless. The XM177E2 may have been a stopgap solution in its time, but it became the ancestor of a lineage of carbines that continue to define modern warfare.

To stand before the XM177E2 today is to confront a story etched in sweat, blood, and sacrifice. It is to hear the phantom echoes of its sharp crack in the jungle night. It is to imagine its muzzle flash breaking the dark as Special Forces soldiers moved with deadly purpose through hostile terrain.

It is a weapon that represents both failure and redemption—the failure of the E1, redeemed by the battle-forged improvements of the E2. It is a story of innovation under fire, of lessons learned the hard way, and of soldiers whose survival depended on every pull of its trigger.

The XM177E2 is not just a relic of war. It is a voice from the past, still whispering of courage, survival, and the relentless drive of warriors to adapt, overcome, and endure.