Know Where Your Ammo Comes From! Project Pole Bean: How Sneaky Green Berets Blew Up a Few Guns and Frightened an Entire Army

In 1968, American troops in Vietnam reported scattered incidents where dead NVA soldiers were found with parts of their exploded rifles protruding from their skulls. Technical Intelligence attributed this to poor metallurgy and bad ammunition. The situation was a little more complicated than it appeared.

Know Where Your Ammo Comes From! Project Pole Bean: How Sneaky Green Berets Blew Up a Few Guns and Frightened an Entire Army
The Type 56 rifle could handle 40,000 p.s.i. of chamber pressure. The kinetic disassembly in the picture was caused by firing a modified cartridge which produced 250,000 p.s.i. This blew up the gun and threw the bolt straight back through the top cover.

My uncle Harvey was a Green Beret who served with MAC-V SOG in Vietnam. When I was a kid, I pestered him to tell me about their missions. They would go deep into the North Vietnamese Army (NVA) base areas and tap communications wire, take prisoners and do bomb damage assessment.

My favorite story was how they used to carry in ammunition and put it in NVA storage bunkers. Well, to be accurate, they put it BACK in the bunkers and some other places too.

Military Assistance Command Vietnam’s Studies and Observations Group (SOG) was America’s top-secret special operations task force in the Vietnam War. SOG’s operators worked directly for the Joint Chiefs, executing highly classified and deniable missions in Laos, Cambodia, and North Vietnam. From 1966 to 1968, SOG was commanded by Colonel John K. Singlaub.

Singlaub was an old school unconventional warfare pro. He parachuted behind German lines with the OSS in August 1944 to fight with the French Resistance fighters supporting the D-Day invasion. 

After WW2, Singlaub joined the Central Intelligence Agency (CIA) and worked in Manchuria during the Chinese Civil War. In 1951 he became Deputy Chief of the CIA station in South Korea. Later he ran CIA operations in Manchuria and led troops in the Korean War. He was the perfect guy to run SOG.

SOG teams ran deniable missions into Laos and Cambodia to gather intelligence, wiretap communications, kidnap personnel, ambush convoys, raid supply dumps, plant mines, and generally spread the joys of unconventional warfare across the NVA rear.

Know Where Your Ammo Comes From! Project Pole Bean: How Sneaky Green Berets Blew Up a Few Guns and Frightened an Entire Army
SOG recon teams normally consisted of two or three American Green Berets and four to six indigenous soldiers. 

This may not sound as romantic as fighting front line infantry units, but without a secure rear, the bad guys at the front got less food and ammunition. As these operations began to effect NVA operations, several divisions of NVA regulars were put on security missions along the Ho Chi Min trail.

Special NVA units were formed and specific tactics were developed to find and kill SOG teams. Landing zones were watched, trackers and dogs were deployed, and a system of communications established to allow a rapid response to any contact with SOG. While finding the NVA could be a problem for infantry units, they trucked guys in for the SOG teams to mow down.

While skulking around, these teams often encountered ammo caches with millions of rounds.  Being Green Berets, their first inclination was to steal the ammo, but there was just too much of it and it was in very remote areas. Demolition was not feasible as it would only scatter small-arms ammunition, not destroy it.

They could have booby-trapped the caches so that when the NVA picked up a case it would blow up but that would have only impacted a small number of enemy soldiers and the NVA could develop countermeasures. Singlaub came up with a deeper game. He would take some of the ammo, booby trap the individual rounds of ammunition, and give them back.

Like most unconventional tactics, ammunition sabotage was nothing new.  In one well-documented operation, the British slipped exploding rifle cartridges into enemy caches during the Second Matabele War (1896-1897) in what is now Zimbabwe. The British scouts were led by an American, Frederick Russell Burnham, who probably put them up to it.

During World War, the British Special Operations Executive (SOE) and American Office of Strategic Services (OSS) collaborated on Operation Natterjack to plant sabotaged ammunition in the Japanese supply chain. OSS Detachment 101 distributed the ammunition in Burma but little is known about the results.

Know Where Your Ammo Comes From! Project Pole Bean: How Sneaky Green Berets Blew Up a Few Guns and Frightened an Entire Army
NVA soldiers with AK-47 rifles.

The SOG ammunition enhancement plan was briefed all the way to the Joint Chiefs of Staff in the Pentagon. On August 30, 1967, they approved the plan and two weeks later, Singlaub watched a CIA technician load a sabotaged 7.62X39 mm cartridge into a bench-mounted AK rifle at Camp Chinen, Okinawa. “It completely blew up the receiver and the bolt was projected backwards,” Singlaub said, “I would imagine into the head of the firer.”

The first cartridges were reloaded with an explosive powder similar to PETN high explosive. The problem was that this white powder looked nothing like Chinese gunpowder, so if the NVA pulled apart an altered round it would be detected. SOG’s technical expert, Ben Baker obtained a substitute explosive that so closely resembled gunpowder that it would pass inspection by anyone but an ordnance expert.

Know Where Your Ammo Comes From! Project Pole Bean: How Sneaky Green Berets Blew Up a Few Guns and Frightened an Entire Army
NVA soldiers armed with (from left to right) SKS rifle, RPD light machinegun and AK47. All of these weapons fire the same 7.62X39 ammunition simplifying logistics.

Communist block 7.62X39 weapons such as the SKS, RPD, AK47, and Type 56’s could handle up to 40,000 p.s.i. of chamber pressure. The new powder produced 250,000 p.s.i. enough to blow up the weapon and kill the soldier shooting it.

The secret CIA lab in Okinawa developed more than just rifle ammunition.  Tiger striped fatigues, Time Delayed fuses and Astrolite explosive (developed from NASA rocket fuel) all came from this small group of evil geniuses. Later CIA ordnance experts developed a special fuse for the 82 mm mortar round that would detonate inside the mortar tube. Rounds for 12.7x108mm heavy machine guns soon followed.

After the process was developed in the lab, a specialized ordnance team was formed to modify the ammo. Chinese AK bullets were sealed into steel cases with a thick coat of lacquer where the bullet entered the case. The rounds were pulled apart by hand and the powder was replaced with a high explosive substitute. The bullets were then re-seated and the ammo cans and crates resealed just like the original.

While operating deep in enemy territory on other missions, Green Berets carried booby-trapped rounds and cases of ammunition cases with them and slipped them into the enemy ammunition supply chain whenever possible. If the SOG team encountered an ammo dump, they would plant a case of doctored ammo. 

Know Where Your Ammo Comes From! Project Pole Bean: How Sneaky Green Berets Blew Up a Few Guns and Frightened an Entire Army
82 mm mortar ammo was not stored as loose rounds, it came in three-round, wooden cases. SOG teams must have been very amused by this concept to volunteer to carry a 28 pound case of mortar rounds in addition to all of their other equipment.

When a SOG team ambushed an enemy patrol, they would load one round into an AK magazine or RPD belt left on enemy bodies with the expectation it would be recovered and re-used. When the gun later exploded, all the evidence of sabotage would be destroyed as the round was fired.

The rigged ammo turned up all over the battlefield, weapons exploded, killing NVA riflemen and sometimes entire mortar crews. Now it was time to initiate SOG’s black psychological operations exploitation plan. The strategic objective was to aggravate the Vietnamese traditional distrust of the Chinese. 

At the tactical level, individual soldiers questioned the safety of their Chinese-supplied arms and ammunition. One forged Viet Cong document spread rumors of exploding ammunition while another acknowledged ammo problems resulting from poor Chinese quality control.

The forged document stated, “Only a few thousand such cases have been found thus far,” and concluded, “The People’s Republic of China may have been having some quality control problems but these are being worked out. We think that in the future there will be very little chance of this happening.”

Know Where Your Ammo Comes From! Project Pole Bean: How Sneaky Green Berets Blew Up a Few Guns and Frightened an Entire Army
Chinese ammunition was shipped in sealed metal cans with lot numbers stenciled on top. These type cans are still in use. I have seen thousands of these cans all over the Middle East and Afghanistan. American AK shooters who use surplus ammunition are very familiar with “Spam” cans and the big can openers shipped in each wooden case of two cans.

Any NVA soldier, looking at ammunition lot numbers, would see that, due to the length of the supply chain, his ammo had been loaded years earlier. No fresh ammo could possibly reach soldiers fighting in the South for years.  The possibility of compromised ammunition would never disappear.

Know Where Your Ammo Comes From! Project Pole Bean: How Sneaky Green Berets Blew Up a Few Guns and Frightened an Entire Army
Military Assistance Command Vietnam (MACV) Technical Intelligence Brief No. 2-68

Military Assistance Command Vietnam (MACV) published a Technical Intelligence Brief titled “Analysis of Damaged Weapons” which was widely circulated to U.S. and South Vietnamese units. The study examined several exploded AKs, concluding they were destroyed by “defective metallurgy resulting in fatigue cracks” or “faulty ammunition, which produced excessive chamber pressure.” Enemy agents passed this information directly back to Hanoi.

American G.I.s were warned against using enemy weapons in public service announcements on Armed Forces Radio and TV which were duly monitored by the Vietnamese. The Army Times warned, “Numerous incidents have caused injury and sometimes death to the operators of enemy weapons.”

Know Where Your Ammo Comes From! Project Pole Bean: How Sneaky Green Berets Blew Up a Few Guns and Frightened an Entire Army
NVA 82mm Mortar Team laying in their gun.

Mortars work by using a low pressure charge to throw a bomb with a fragment producing case down range. There is a firing pin in the bottom of the tube which hits a primer in the mortar round when the round is dropped in the tube. A fuse ignites the main charge when it hits the target. The modified fuse blows the main charge inside the mortar tube.

As the rigged ammo spread through the system, Forward Air Controllers observed mortars in Laos, Cambodia, and even in Southern Vietnam blown apart in a star shape pattern. Usually, there were a few 3-4 NVA bodies present.

Planting munitions was risky. On November 30, 1968, a helicopter carrying a SOG team with seven cases of CIA modified 82 mm mortar ammunition was flying 20 miles west of the Khe Sanh Marine base. It was hit by 37 mm anti-aircraft fire and exploded in mid-air with no survivors. The remains of Maj. Samuel Toomey and seven U.S. Army Green Berets were recovered at the crash site 20 years later.

Despite the warnings, American soldiers fired captured arms, and at least one souvenir AK exploded, inflicting serious injuries. To avoid ironic self-injury, SOG stopped using captured ammunition in their own AKs and RPD machine guns and purchased 7.62X39mm ammunition from Finland. This ammo, which SOG’s Green Berets fired at the NVA had been manufactured in a Soviet arsenal in Petrograd. Thank you, Comrades.

To keep it secure, the code name changed through the course of the war. The Project began as Eldest Son, then was changed to Italian Green and ultimately Pole Bean.

In mid-1969, articles in the New York Times and Time magazine compromised the mission. Ordered by the Joint Chiefs to dispose of their remaining stockpiles of ammo, SOG teams rushed to insert multiple missions on the Laotian border to get rid of the stuff before their authority expired.

Even after the enemy was aware of the sabotaged ammunition, the program was psychologically useful. The NVA could never again trust their ammo supply. Radio intercepts confirmed the NVA’s highest levels of command were disturbed by their exploding weapons, Chinese quality control, and sabotage.

Declassified reports reveal that SOG operatives inserted 3,638 rounds of sabotaged 7.62 mm, plus 167 rounds of 12.7 mm and 821 rounds of 82 mm mortar ammunition over the life of the program.

Like all great ideas, this one has been copied. Doctored ammunition of undetermined source is still turning up all over the world. There are reports of a special thermite rifle round that melts in the chamber destroying the gun with no injury to the shooter. This protects innocent users such as American G.I.s while denying weapons to the bad guys.

Who knows if the Americans did this or it was just a happy accident.

Former Green Beret Jack Murphy, author of “Murphy’s Law”, tells the story of attempting to shoot a captured SVD in Iraq. The primer popped and the round got intensely hot melting the chamber and barrel together. No need for fake Technical Intelligence Bulletins to protect friendlies here.

In Iraq and Afghanistan, most of the doctored ammunition is high-explosive 120-millimeter and 82-millimeter mortar rounds. Like SOG rounds, the fuses are altered so they explode inside the mortar tube, destroying the entire mortar system and crew.

The advantage of this particular sort of booby trap is narrow targeting. Unlike rifle ammunition, which might turn up with a homeowner keeping a firearm to protect his family, mortar rounds do not have legitimate home security use.

This 120mm Russian mortar had an unexpected detonation. There are reports the Syrian state military launched an operation secretly passing booby-trapped rounds to insurgent fighters at illegal arms bazaars across the middle east. The New York Times thinks that they got the idea from the US.

While it is gratifying to see the direct results of your efforts, it can be more effective to set the conditions for success and then stand back and watch the enemy do the work for you. The results from Eldest Son, Italian Green and Pole Bean exceeded all expectations.

Green Berets are trained to anticipate the second and third order effects of their actions. These projects killed hundreds, frightened the entire North Vietnamese Army, and sowed distrust between Vietnam and China at the highest levels of government for years to come. In 1979 the two countries went to war.

It pays to know the source of your ammunition and where it has been before it got to you.

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  • navycwo October 20, 2022, 11:39 am

    I recall hearing about Navy Seals in Viet Nam doing the same thing; but substituting C-4 for he gunpowder in AK rounds.

  • AK October 14, 2020, 5:29 pm

    I was about a year too young for VN, but did 24 years active in the USAF 1077-2001. As a lifelong gun nut, I bought every gun rag out there as a teen….I read about this back sometime around 1970 and thought, you sneaky bastards…with a big grin….

  • October 12, 2020, 6:21 pm

    Yep I was in all of these places on the ground and in the air. Black Horse and Bear Cat as well. I have a photo of me standing in front of MACV headqarters in 1969 when I drove my 1st SGt to a meeting down there. It was all highly classified and a bit unusual to drive instead of fly ? Now that was one hell of an interesting road trip in a jeep, just me and him with all our gear and a lot of ammo from Black Horse to MACV in Bien Hoa ., what a trip that was. Everyday I am quite amazed I survived all the different events and lived to talk about it with no permanent injuries. In fact as crazy as it sounds I am stronger and more fit today in 2020 than I was then as a 19-20 year old skinny kid.

    On the way back we ran out of gas in the midlde of a rubber tree plantation and had to secure ourselves over nite until the next day when an ambulance and two APCs and a duece and a half with a quad 50 on it came by from the 25th and we got some fuel and got back to base camp. That nite was well past a hair ball event but I slept anyway. Our spare GI can on the back of the jeep had bullet holes and some frags in it and all our spare fuel leaked out while driving apparently. we pushed the jeep off the road into some bushes and took turns on guard duty all nite until our rescuers came along the next morning and even that meeting was very touch and go as they did not know if we were enemy from a distance. I had to go into the middle of the road and wave at them. They stopped and sent two guys up each side of the road to check us out and got us going again . We all laughed our asses off even though we just defied one more crazy event of many !

    In retrospect it may also sound crazy , but now i am very glad I experienced it all. It was a huge changing point in my life and if it did not kill you it made you much stronger. Everyday I fully appreciate I was a lucky one ! And today I am well past thankful for my health and well being. Anybody can do the same thing.

  • Walleye October 12, 2020, 4:12 pm

    It’s surprising that some vigilante (Charles Bronson type) hasn’t already done this in some large metro area like north St. Louis City, Detroit, Chicago South side, etc. Its easy to imagine what affects this would have on the local members of the Urban Wildlife Society if one of them picked up a box of “hot” 9mm ammo lying around “discarded” on the street corner and then tried to spray some bullets in the direction of his rival gang members.

  • Don October 12, 2020, 9:29 am

    When I told another vet about this ammo, he came to a relization. He had been in quite a few close combat engagements and and watched quite a few PAVN (NVA) soliers get killed when their rifles blew up. He had made the assumption that the guns were poorly made. Once he knew about this ammo it expalined the mystery behind the explosions. This was also the reason vets bringing back war trophy SKS carbines could not bring back any ammo with them. This was a good operation.

    • Mike in a Truck October 12, 2020, 12:32 pm

      This is why I never used battle field pickups. My buddies and I treated them the same way as VC grenades. We called them “suicide rats”. As they were made out of discarded C ration cans.Wouldnt touch them with a ten foot pole.

  • Bad Penguin October 12, 2020, 9:22 am

    Back in the late 70’s an ROTC instructor told us that the first VC he encountered on his first tour had the bolt of his exploded AK sticking out of the back of his head. Well Done SOG.

  • Roger J October 12, 2020, 8:28 am

    I remember hearing about this years ago. I found myself chuckling while reading this article.

  • Big Al 45 October 12, 2020, 8:08 am

    I was at the the Knob Creek Machine Gun shoot in ’86 when both a Machine Gun and an FNL blew up, it was reported that the ammo was from Argentina, and had been booby trapped by the Brits, perhaps MI 6?
    While I don’t know the validity of the claim, it certainly dampened sales of Argentinian surplus ammo .

  • Philip Viavattine October 12, 2020, 7:05 am

    I was one of the first combat units that landed in RSV in April 1965 and we heard about this type of sabotage being conducted, so if US Marines knew about this little caper before it was officially started I wonder about it’s secrecy. We thought it was a pretty good idea and perhaps it wasn’t part of the SOG’s mission. The last thing a combat soldier want’s to question is his ammo & his weapons.

  • Michael D'Amico October 11, 2020, 2:37 pm

    Great article, I wouldn’t have known about this otherwise. Thanks

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