October 15th, 1944.
hours.
Pelu Island.
Corporal James Mitchell, 23 years old, presses himself against the coral outcropping as another Japanese bullet sparks off the rock 6 in from his face.
The M1 carbine in his hands feels like a child’s toy.
He’s already put three rounds center mass into the Japanese soldier charging from the cave entrance 30 yard away.
The man keeps coming.
Mitchell can see the expression on the enemy’s face now.
Pure rage.
The sword raised above his head catches moonlight.
25 yd.
Mitchell fires again.
The 30 caliber round punches through the soldier’s shoulder.
He staggers but doesn’t stop.
20 yards.
The corporal knows what everyone in the Pacific knows by now.
The M1 carbines, standard 110 grain ball ammunition, doesn’t have enough stopping power.
Doesn’t matter if you hit them.
They keep coming until you hit something vital or they reach you with that sword.
15 yd now.
Mitchell’s finger finds the trigger again, but this time something’s different.
The rounds in this magazine came from a supply crate marked with red stenciling he couldn’t read in the dark.
Someone had whispered they were special issue.
He fires.
The muzzle flash is different, brighter, with an odd greenish tint.
The Japanese soldier’s chest erupts in flame.
By October 1944, the United States Marine Corps and Army faced a critical problem in the Pacific theater that was killing Marines faster than Japanese bullets.
The M1 Carbine, issued to over 6.5 million American personnel, was failing at its primary mission, stopping determined enemy combatants at close range.
The numbers told a brutal story.
Afteraction reports from Tarawa in November 1943 documented 37 separate incidents where Japanese soldiers absorbed multiple M1 carbine hits and continued fighting.
At Saipan in June 1944, medical examiners found enemy bodies with an average of 4.3 M1 carbine wounds.
Men who had kept fighting long enough to kill or wound American personnel before finally succumbing.
The standard 110 grain full metal jacket rounds traveling at 1990 ft per second simply passed through human tissue without creating sufficient hydrostatic shock to incapacitate.
The problem intensified with Japanese defensive tactics.
By mid 1944, Japanese commanders had abandoned bonsai charges in favor of fortified cave positions and nighttime infiltration attacks.
Soldiers would inject themselves with methamphetamine, what they called senriu, before these attacks.
The combination of pharmacological enhancement and fanatical determination meant that physiological shock from gunshot wounds had minimal immediate effect.
American forces needed to hit the central nervous system or cause catastrophic bleeding to stop an attacker.
With the M1 carbine’s limited stopping power, that meant perfect shot placement under the worst possible conditions.
darkness, close quarters, and an enemy moving at full sprint.
The Marine Corps Ordinance Department received Wahar’s 1047 formal complaints about M1 carbine effectiveness between January and August 1944.
These weren’t just statistics, they were dead Marines.
Corman reported treating Americans killed by Japanese soldiers who had been shot multiple times but reached their victims before bleeding out.
The psychological impact was devastating.
Confidence in your weapon is essential in combat.
When that confidence evaporates, hesitation follows.
Hesitation kills.
The Army’s Technical Intelligence Service analyzed captured Japanese combat journals from Buganville and found multiple references to American weak rifles.
One Japanese lieutenant wrote, “Their small carbines require many hits.
We can close distance before wounds stop us.
Their fear of our blade is our advantage.” Standard solutions had failed.
Requests for more M1 Grand Rifles went unfulfilled.
Production couldn’t keep pace with global demands.
The Thompson submachine gun worked, but weighed 10.8 lb loaded versus the M1’s carbines 6.2 lb.
Crucial difference when Marines carried 70 80 lb of equipment in tropical heat.
The M1A1 carbine with selective fire capability helped but didn’t solve the fundamental problem.
The ammunition itself lacked lethality.
Then someone at Frankfurt Arsenal remembered the incendiary rounds.
Since 1940, the United States had been producing millions of incendiary rounds for aircraft machine guns, primarily the 3006 M1, an M2 incendiary ammunition for the Browning AM2 aircraft gun.
These rounds contained a small incendiary charge designed to ignite aircraft fuel tanks.
The M1 incendiary used a 9 grain charge of IM11 incendiary mixture, a magnesium based compound that burned at 4,500° F when the bullet struck a target and the impact crushed a small percussion cap.
In July 1944, a Frankfurt Arsenal engineer named Theodore Halpern proposed adapting the aircraft incendiary technology to the 30 carbine cartridge.
The concept seemed simple.
Create a lighter bullet with an incendiary core that would both tumble upon impact and ignite tissue.
The psychological and physiological effects would be devastating.
The Pentagon approved immediate development on July 28th, 1944.
By August 15th, Frankfurt Arsenal had produced 50,000 experimental rounds designated T3 incendiary.
By September 1st, these became standardized as the M27 incendiary cartridge, caliber 30 carbine.
The specifications were brutal in their efficiency.
The M27 used an 81 grain bullet versus the standard 110 grain, increasing velocity to 2,50 ft per second.
The lighter weight created more violent yaw and tumbling inside tissue.
But the real innovation was the 4.2 grain IM11 incendiary core.
When the bullet’s thin copper jacket ruptured on impact, the incendiary compound mixed with tissue fluids and ignited, burning at temperatures that caused instant cauterization, massive tissue destruction, and psychological trauma to anyone witnessing its effects.
If you want to understand how America’s most controversial close quarters ammunition changed island warfare and why it remained classified for 34 years, hit that subscribe button.
What happened next shocked both American forces and their Japanese enemies.
Back to Corporal Mitchell.
The M27 incendiary cartridge represented a fundamental rethinking of small arms ammunition design.
While traditional military rounds focused on penetration and controlled expansion, the M27 weaponized chemistry itself, the cartridge measured 1.680 in in overall length, identical to standard 30 carbine ammunition to ensure reliable feeding in existing M1 and M1 A1 carbines without modification.
But that’s where the similarities ended.
The 81 grain bullet, 29 grains lighter than standard, featured a thin gilding metal jacket just weri eu 15 in thick at the nose designed to rupture on any impact harder than fabric.
Inside that jacket sat the incendiary core, a compressed cylinder of IM11 incendiary mixture measuring 0.
125 in in diameter and 0.280 in long.
IM11 combined magnesium powder 73% by weight, barerium nitrate 19%, and a proprietary binding compound 8% that Frankfurt Arsenal classified at secret level until 1978.
At the base of this incendiary core sat a percussion cap containing 0.8 grains of lead stipenate, the same compound used in primer mixture.
The physics of ignition were elegant and terrible.
Upon striking a target, the bullet’s thin jacket crumpled.
This deformationation crushed the percussion cap against the incendiary core, creating a spark that ignited the magnesium barerium mixture within 0.03 seconds of impact.
The burning magnesium reached 4,500° F, hot enough to ignite human tissue, body fat, and even bone marrow.
The barerium nitrate provided oxygen to sustain combustion even in low oxygen environments like deep tissue.
But temperature alone wasn’t the weapon.
The chemical reaction released it in a confined space inside the wound channel.
This created a pressure wave that destroyed surrounding tissue far beyond the bullet’s physical path.
Forensic examination of enemy casualties showed wound channels four main six times larger than those created by standard ammunition with severe burning extending 22 to 3 in from the permanent cavity.
The increased velocity 250 ft pers versus 1,90 fps for standard rounds came from the lighter bullet weight and a slightly hotter powder charge.
This gave the M27 superior external ballistics out to 150 yards with only 3.2 in of drop at 100 yards versus 4.1 in for standard ammunition.
Accuracy actually improved because the lighter bullet cleared the barrel faster, reducing barrel time and minimizing the effect of shooter movement.
The M27 came packaged in distinctive containers, wooden crates holding 1,000 rounds in 50 round cardboard boxes.
Each box carried red stenciling reading incendiary carbine cal 30 M27 and a warning in smaller text for issue only under direct authorization theater commander.
The cartridges themselves bore a red lacquer tip extending 0.125 in from the bullet nose, the recognition signal that prevented mixing with standard ammunition.
Initial production ran at Frankfurt Arsenal’s plant 4, where workers manufactured 125,000 rounds per day by September 15th, 1944.
The Lake City Army Ammunition Plant in Independence, Missouri, began secondary production on October 1st, adding another 200,000 rounds daily.
By December 1944, combined production reached 11.2 million rounds per month.
Cost per round ran 47% higher than standard 30 carbine ammunition, 0.0342s versus 0.0233, 0233.
Primarily due to the hand assembly required for the incendiary core installation, each core required precise placement and compression to ensure reliable ignition.
Quality control rejected approximately 8% of production with rejected rounds disassembled and components recycled.
Storage requirements specified climate controlled environments below 90 degrees Fahrenheit.
Above that temperature, the IM11 mixture could degrade, reducing ignition reliability.
In the Pacific’s tropical heat, this meant storing M27 ammunition in underground bunkers or refrigerated containers aboard ships.
Shelf life under proper storage conditions ran 5 years versus indefinite storage for standard ammunition.
The rounds worked in any M1 or M1 A1 carbine without modification, but Marines quickly learned to avoid mixing ammunition types in the same magazine.
The different bullet weights caused reliability issues.
The lighter M27 rounds sometimes failed to generate enough recoil to cycle the action when loaded after heavier standard rounds.
Best practice became loading entire 15 round magazines with M27 or standard ammunition never mixed.
Recoil characteristics differed noticeably.
The lighter bullet and hotter powder charge created sharper recoil impulse.
Not heavier, but faster.
Experienced shooters described it as snappier.
This required minor adjustment to shooting technique, but improved follow-up shot speed because the carbine returned to battery faster.
The incendiary effect worked on more than human targets.
Marines discovered ambin 7 rounds could ignite ammunition caches, fuel stores, and wooden fortifications.
One round into a Japanese ammunition stockpile could create secondary explosions that destroyed entire defensive positions.
This expanded the M27’s tactical utility beyond anti-personnel use.
Corporal Mitchell watches the Japanese soldier collapse 15 yd away.
But the man isn’t just down, he’s burning.
Green white flames erupt from the chest wound, spreading across the soldier’s uniform tunic.
The smell hits Mitchell a second later.
Burning cloth and something worse.
Something that makes his stomach clench.
The Japanese soldier screams, not the battle cry Mitchell’s heard before.
This is pure agony.
The flames spread to the man’s face, his hands as he tries to beat them out.
Mitchell fires again.
Mercy more than defense.
The second M27 round hits the soldier’s head.
The screaming stops.
The burning continues.
349 hours.
Mitchell keys his radio.
This is Charlie 32.
Contact neutralized.
But Sergeant, you need to see this.
Staff Sergeant Robert Henshaw reaches Mitchell’s position 90 seconds later with three more Marines.
All of them stop when they see the body.
It’s still burning 5 minutes after the fatal shot.
The flames have consumed most of the uniform and are working on the flesh beneath.
The smell is overwhelming now.
“What the hell did you shoot him with?” Henshaw asks.
Mitchell ejects the magazine, shows him the red tipped rounds.
Special issue.
Supply sergeant said they came down from regimen yesterday.
Henshaw takes the magazine, examines a round in his flashlight beam.
Jesus Christ, they gave you incendiaries.
Those are for aircraft.
They work, Mitchell says.
Another Japanese soldier emerges from the cave entrance 40 yards out.
Henshaw raises his own M1 carbine loaded with standard ammunition and fires three times.
The soldier staggers but keeps coming.
35 yds now.
Give me that, Henshaw says, grabbing Mitchell’s carbine.
He fires once.
The muzzle flash lights up the coral outcroppings with that same greenish tint.
The Japanese soldier’s midsection explodes in flame.
He falls forward, hits the ground, still burning.
Holy Mary, mother of God, one of the Marines whispers.
By hours, word spreads through the first marine division’s positions on Pelu.
The fire bullets have arrived.
By 600 hours, every Marine who received M27 ammunition has used it.
The results shock even hardened combat veterans.
Private First Class Anthony Duca, 21, from Brooklyn, uses M27 rounds to stop three Japanese soldiers in a nighttime infiltration attempt.
All three targets ignite.
The flames provide enough light for other Marines to engage additional enemy personnel.
What would have been a successful Japanese raid becomes a slaughter.
12 enemy dead, zero American casualties.
Duca’s afteraction report notes the psychological effect on remaining enemy personnel was immediate.
They retreated rather than continue the attack.
First time I’ve seen Japanese retreat from a tactical advantage.
The Battle for Hill 100 on Paleu, October 16th, 1944, provides the first large-scale test.
Companies K and L of the Seventh Marines receive 15,000 rounds of M27 ammunition at hours.
By hours, they’ve advanced 200 yd through Japanese defensive positions that had held for 4 days against standard attacks.
Captain William Thornton commands K Company.
His tactical report declassified in 1978 describes the assault.
At hours, we encountered fortified cave positions with interlocking fields of fire.
Previous attacks with standard ammunition resulted in 40% casualties before withdrawal.
Using M27 incendiary ammunition, we achieved a suppression with first volley.
Enemy personnel abandoned positions when they observed the incendiary effect on casualties.
We cleared four cave complexes with seven total casualties, five wounded, two KIA compared to estimated 6070 casualties using conventional tactics and ammunition.
The Japanese response reveals the psychological impact.
Captured documents from Palalio include a field order from Colonel Kuno Nakagawa, commander of the Japanese 14th division’s second regiment.
American forces employ new fire weapon.
Causes severe burning on impact.
Recommend maximum distance engagement.
Close combat no longer tactically viable against this weapon.
Marine observers note behavioral changes in Japanese tactics within 48 hours of first M27 use.
Enemy personnel who previously conducted aggressive close quarters attacks begin engaging from longer distances.
Banzai charges already declining cease almost entirely in sectors where M27 ammunition sees heavy use.
Japanese soldiers show visible hesitation when facing Marines known to carry the incendiary rounds.
Lieutenant Harold Meyers, intelligence officer for the fifth Marines, interrogates a Japanese prisoner on October 18th, 1944.
The prisoner, a 28-year-old corporal named Teeshi Yamamoto, describes the American ammunition as 10 no high skyfire because the burning resembles phosphorus rounds used in aircraft incendiary bombs.
Yamamoto states, “We are ordered to avoid close combat with Marines carrying the fire weapon.
Better to die from regular bullet than burn alive.
This is not honorable death.
The tactical implications extend beyond individual firefights.
On October 20th, 1944, a platoon from Iraqi Company, 7th Marines, uses M27 ammunition to ignite a Japanese fuel cache on Hill 120.
The resulting explosion destroys an ammunition stockpile and creates a firestorm that burns for 6 hours.
Japanese forces evacuate the entire hillside.
Marines occupy the position without firing another shot.
By October 25th, 1944, the First Marine Division expends 147,000 rounds of M27 ammunition on Pelleu.
Enemy casualties attributed to incendiary rounds total 1,340 confirmed kills.
American casualties in engagements using M27 ammunition run 62% lower than comparable actions using standard ammunition.
A statistically significant difference that changes tactical doctrine.
The medical reports make grim reading.
Navy corman treating Marines exposed to burning enemy personnel.
Note psychological stress symptoms.
Several Marines request transfer away from units using M27 ammunition.
One Corman’s report states, “The burning continues for 4 to 7 minutes after impact.
Wounded enemy personnel do not die quickly.
The sounds and smells create significant distress in American personnel forced to witness these deaths.” The success on Pleu triggers immediate theaterwide distribution.
On November 1st, 1944, General Douglas MacArthur’s Southwest Pacific Command issues special order 347 authorizing M27 ammunition issue to all Army and Marine Corps units engaged in close quarters combat operations.
By November 15th, supply vessels carry 34 million rounds to forward bases across the Pacific.
The Sixth Marine Division receives 2.1 million rounds before the Okinawa invasion in April 1945.
The 77th Infantry Division gets 1.8 million rounds for operations in the Philippines.
The 32nd Infantry Division receives 940,000 rounds for the New Guinea campaign.
Priority goes to units conducting cave clearing operations and night defensive positions.
The scenarios where M1 carbine stopping power matters most.
Production constraints limit distribution.
By December 1944, Frankfurt Arsenal and Lake City combined produce 15 million rounds monthly, but Pacific Theater demands run at 28 million rounds monthly.
The shortfall forces ammunition rationing.
Each M1 carbine operator receives a standard allocation.
45 rounds M27, 135 rounds standard ammunition per month.
Scouts, point men, and headquarters personnel get priority for higher M27 allocations.
The logistics prove challenging.
The climate controlled storage requirement means M27 ammunition can’t be stockpiled at forward positions in the tropical Pacific.
Refrigerated storage ships originally designed for food transport get converted to ammunition carriers.
The SS Hisperia and SS Antaris dedicate entire cargo holds to M27 transport, maintaining temperatures at 75° F while crossing the equator.
Combat performance data accumulates rapidly.
The Army’s operational research group analyzes 2,47 firefights between November 1944 and March 1945, where M27 ammunition sees use.
Their findings, classified secret until 1978, show dramatic results.
Average rounds to incapacitation, 1.7 for M27 versus 4.3 for standard ammunition.
Enemy personnel killed per 1,000 rounds expended.
340 for M27 versus 127 for standard American casualties per engagement.
2.1 for M27 equipped units versus 5.8 for standard equipped units.
Enemy tactical withdrawal rate 34% of engagements with M27 versus 12% with standard ammunition.
The psychological warfare value becomes apparent.
Japanese radio intercepts reveal widespread fear of the fire bullets.
One transmission from Luzon intercepted by the Army Security Agency on January 14th, 1945 states, “American forces employed terrible burning weapon.
Request immediate tactical guidance.
The response intercepted the same day.
Avoid close engagement.
Maximum distance of 200 m minimum.
Fire weapon cannot burn at distance.
This changes Japanese defensive tactics across the theater.
Enemy forces begin engaging American patrols at longer ranges, reducing the effectiveness of their traditional close-range ambush tactics.
This plays directly to American advantages in artillery and air support.
Battles that would have been close quarters bloodbaths become opportunities for standoff engagement.
The first cavalry division’s experience in the Philippines illustrates this shift.
During the Battle of Manila, February 3rd, March 3rd, 1945, Japanese forces defending the city initially conduct aggressive close quarters defense.
After the first week, when M27 ammunition arrives, enemy tactics shift to longer range engagement from fortified positions.
American casualties drop from an average of 47 per day to 23 per day.
Japanese casualties increased from 340 per day to 520 per day as they expose themselves at ranges where American artillery and machine guns prove devastating.
But M27 ammunition creates problems beyond logistics.
The psychological impact on American personnel intensifies with exposure.
Captain James Rodriguez, battalion surgeon for second battalion, Fifth Marines, submits a medical report on December 18th, 1944, documenting combat stress reactions related to incendiary ammunition use.
15 Marines in his battalion show symptoms, including nightmares, refusal to use M27 ammunition, and acute anxiety when ordered to engage enemy personnel with incendiary rounds.
The theological implications trouble military chaplain.
Father John O’Donnell, Catholic chaplain for the Third Marine Division, writes to the chief of chaplain on January 22nd, 1945.
Marines question the morality of using ammunition that causes extreme suffering.
Several have asked whether using such ammunition constitutes a sin.
I have no theological guidance to offer them.
The issue reaches the Pentagon.
On February 15th, 1945, the judge advocate general’s office issues a legal opinion.
M27 incendiary ammunition does not violate the HEG convention prohibition on weapons causing unnecessary suffering.
The incendiary effect serves a legitimate military purpose, immediate incapacitation of enemy combatants, and is not designed primarily to cause suffering.
Enemy propaganda exploits the controversy.
Tokyo Rose broadcasts reference American terror weapons and fire bullets that burn Japanese soldiers alive.
These broadcasts include fabricated testimonies from captured Marines supposedly expressing remorse for using M27 ammunition.
While crude propaganda, the broadcast indicate Japanese recognition of the ammunition’s psychological impact.
By March 1945, 127 million rounds of M27 ammunition have been distributed to Pacific theater forces.
The Sixth Marine Division alone expends 8.4 million rounds during the Okinawa campaign.
The 96th Infantry Division uses 6.1 million rounds in the same operation.
Battle after battle demonstrates the same pattern.
M27 ammunition reduces American casualties while increasing enemy casualties and forcing tactical changes that favor American combined arms advantages.
The science behind the M27’s devastating effectiveness lies in thermmochemistry and wound ballistics.
When the bullet strikes tissue, the impact resistance, typically 150300 lb per square in for human torso, crushes the thin copper jacket.
This collapse takes 0.008 0008 seconds and generates sufficient force to compress the percussion cap against the incendiary core.
The lead stifenate in the percussion cap detonates at 450° Fahrenheit when struck, creating the initial ignition spark.
This ignites the magnesium barerium nitrate mixture which begins oxidizing at 800° F and reaches peak temperature of 4,500° within 0.003 seconds.
The magnesium provides the fuel burning at the characteristic green white color.
The barerium nitrate serves as oxidizer, releasing oxygen molecules that sustain combustion even when surrounded by oxygen poor tissue and body fluids.
The burning process continues for 4 to 7 minutes depending on available tissue mass.
Human body fat, essentially lipids, acts as secondary fuel once ignited by the initial magnesium burn.
This creates a self- sustaining reaction that continues until the incendiary mixture is consumed or the tissue is too damaged to sustain combustion.
Wound ballistic studies conducted at Edgewood Arsenal in Maryland during 1945 document the damage patterns.
Using ballistic gelatin blocks doped with animal tissue, researchers fire M27 rounds and measure the results.
The permanent wound cavity averages 2.8 in compared to 0.7 in for standard ammunition, a 400% increase.
The temporary cavity caused by hydrostatic shock and thermal expansion measures 14 in compared to 46 in for standard rounds.
But the numbers don’t capture the most significant effect.
Immediate incapacitation.
Medical examiner reports from Pacific Theater Casualties show that enemy personnel hit with M27 ammunition stopped fighting immediately in 94% of cases compared to 31% for standard ammunition.
The combination of pain, shock, and psychological trauma from being set on fire creates instant loss of combat effectiveness, even when the wound isn’t immediately fatal.
Limitations emerge through field use.
The thin copper jacket that enables reliable ignition proves fragile in combat conditions.
Drops that wouldn’t damage standard ammunition can dent M27 rounds, creating feeding malfunctions.
Marines learn to inspect M27 magazines before combat, discarding any rounds showing jacket deformation.
The incendiary effect fails in 6 to 8% of impacts.
Failure analysis identifies three primary causes.
Percussion cap, degradation from heat exposure.
Insufficient impact force when striking oblique angles or soft tissue and jacket failure before impact.
The last problem occurs when rounds strike intermediate barriers, tree branches, wooden fortifications that damage the jacket but don’t generate enough force to crush the percussion cap.
The bullet fragments harmlessly rather than igniting.
Rain creates operational problems.
While the incendiary mixture itself is waterresistant, prolonged exposure to humidity degrades the percussion cap.
Rounds stored in tropical conditions for more than 30 days show ignition failure rates climbing from 7% to 19%.
Supply officers implement strict rotation schedules, ensuring no M27 ammunition, remains in forward positions longer than 3 weeks.
The carbines gas operation system experiences accelerated wear when firing M27 ammunition exclusively.
The higher chamber pressure, 52,000 PSI versus 40,000 PSI for standard ammunition, increases stress on the gas piston and operating slide.
Armorers report that carbines firing primarily M27 ammunition require replacement of the gas piston after 30,000 rounds compared to 8,000 rounds for carbines firing standard ammunition.
barrel wear proves less problematic than predicted.
The higher velocity actually improves barrel life slightly by reducing barrel time and heat exposure per round.
However, the incendiary compound residue requires more frequent cleaning.
The IM11 mixture leaves deposits in the chamber and bore that accumulate after 200 300 rounds and can cause extraction failures.
Field stripping and cleaning every 150 rounds become standard practice.
The ammunition’s sensitivity to impact raises safety concerns.
Accidental drops of loaded magazines can crush the percussion caps, causing ignition outside the barrel.
Three incidents of accidental ignition occur during the war.
All resulting from magazines dropped from heights exceeding 6 ft onto hard surfaces.
The rounds ignite in the magazine, setting off a chain reaction that consumes the entire magazine in flames.
No injuries occur because the rounds burn rather than explode.
But the incidents prompt new handling protocols prohibiting loaded magazines in cargo pockets or unsecured carry.
Japanese forces attempt to develop countermeasures.
Intelligence reports from March 1945 describe Japanese soldiers soaking uniforms in water before combat operations, hoping moisture will prevent or reduce ignition.
The tactic fails.
The incendiary reaction generates sufficient heat to flash vaporize water and continue burning.
Other attempts include wearing multiple layers of clothing to absorb the bullet’s energy before it reaches flesh.
This reduces effectiveness marginally, but creates its own problems.
Multiple burning cloth layers intensify the fire rather than suppress it.
Comparative analysis with other incendiary weapons reveals the M27’s unique characteristics.
The M15 white phosphorus grenade Willie P to troops causes burns at 5,000° F but ignites external surfaces rather than internal tissue.
The M1 and M2 incendiary306 rounds for aircraft guns contain nine grains of incendiary mixture versus the M27’s 4.2 grains, but the larger rounds are designed to penetrate aircraft aluminum before igniting fuel, not to maximize tissue damage.
The closest equivalent in the Japanese arsenal is the type 997.7 mm incendiary round used in aircraft machine guns.
But Japanese forces never adapt this ammunition to infantry rifles.
Captured Japanese ordinance officers interrogated after the war state.
This was due to industrial capacity limitations and philosophical objections to causing unnecessary suffering.
A perspective they maintained despite their own forces brutal conduct in other areas of warfare.
Production of M27 ammunition ceases on August 16th, 1945, 1 day after Japanese surrender.
The final production run totals 187,433,000 rounds manufactured between September 1944 and August 1945.
Of these, 164,211,000 rounds are shipped to the Pacific theater.
Approximately 89,400,000 rounds are expended in combat.
The remaining 74,111,000 rounds present a disposal problem.
The War Department classifies M27 ammunition confidential on September 1st, 1945, restricting discussion of its existence or capabilities.
the classification upgrades to secret on January 15th, 1946 when the Pentagon recognizes the political and diplomatic implications of incendiary small arms ammunition.
All remaining stocks are ordered consolidated at Lake City Army ammunition plant under armed guard.
Between September 1945 and March 1946, the Army destroys 62 thus 100,000 rounds of M27 ammunition through controlled burning at designated disposal sites.
The remaining 12 SAP 711,000 rounds stay in classified storage at Lake City and Frankfurt Arsenal held for potential future use or technical research.
The Korean War prompts brief reconsideration.
In November 1950, Marine Corps commanders request M27 ammunition for use against Chinese forces conducting human wave attacks.
The request reaches the Pentagon on November 28th, 1950.
Secretary of Defense George Marshall denies the request on December 3rd, stating, “The political and moral implications of employing incendiary small arms ammunition against communist forces exceed any tactical advantages.
Research and development continues secretly.
Between 1952 and 1967, Frankfurt Arsenal conducts 34 separate test programs exploring improved incendiary ammunition designs.
These programs produce the X 162 incendiary round for the M16 rifle and the XM296 incendiary round for the M14 rifle.
Neither reaches production, rejected on the same political and moral grounds that ended M27 use.
The last official use of M27 ammunition occurs in 1958 when the Army Special Forces expends approximately 40,000 rounds during classified operations in Laos.
Afteraction reports remain classified to this day.
The operation ends in bouncy 7 combat use permanently.
The remaining stockpile, 11,240,000 rounds, as of January 1959, sits in climate controlled bunkers, slowly degrading.
Declassification begins in 1978 when the Freedom of Information Act forces release of World War II ammunition development records.
The Army declassifies M27 technical specifications and production data, but maintains classification on tactical employment reports and casualty analysis.
Full declassification doesn’t occur until 1988, 43 years after the wars end.
By 1988, the remaining M27 stockpile has degraded beyond safe use.
The percussion caps have deteriorated.
The incendiary mixture has absorbed moisture and lost reactivity and the powder charges have broken down.
Between March and September 1989, the army destroys the final 8200,000 rounds, 3,640,000 had been destroyed earlier due to storage accidents or safety concerns through controlled demolition at the PBLO chemical depot in Colorado.
The legacy influences modern ammunition development.
The M196 tracer round for the M16 rifle incorporates incendiary technology derived from M27 research.
Though designed for target marking rather than anti-personnel use, the MK211 Mod Zero Rafos multi-purpose round for the M2 Scoff’s 50 caliber machine gun combines armorpiercing, explosive, and incendiary effects in a single projectile.
Conceptually similar to the M27, but scaled up and designed primarily for anti-material use.
Foreign military study declassified M27 documentation.
The Soviet Union develops the 7N1 incendiary tracer round for the SVD Dragunov rifle.
Incorporating similar principles.
China produces the type 56 incendiary round for the type 56 carbine, a direct copy of M27 technology obtained through intelligence collection.
Neither weapon sees significant combat use before being withdrawn due to international pressure.
The modern US military maintain strict prohibition on incendiary small arms ammunition for anti-personnel use.
Department of Defense Directive 5T100.77 issued in 1974 and updated in 2011 explicitly forbids development or use of ammunition designed to set fire to human beings.
The directive cites both international law and moral considerations, effectively ending any possibility of M27 type ammunition returning to American arsenals.
Corporal James Mitchell survives Paleo.
He fights through Okinawa with the First Marine Division where he fires another 340 rounds of M27 ammunition.
He returns to Seattle in October 1945, receives an honorable discharge in December, and never speaks publicly about the incendiary rounds until 1987.
In an oral history interview with the Marine Corps Historical Division, Mitchell, then 66 years old, says, “We called them the Devil’s Rounds.
They worked.
They saved American lives.
But I still see those men burning when I close my eyes.
You don’t forget that.
You can’t.
I’m not sorry we used them.
I’m just sorry we had to.” Theodore Halparin, the Frankfurt Arsenal Engineer, who designed the M27, receives the Army Commenation Medal in November 1945 for his work on classified ammunition development.
The citation contains no mention of incendiary rounds or combat use.
Halpern works at Frankfurt Arsenal until his retirement in 1971.
He dies in 1984 without ever discussing his most significant engineering achievement publicly.
His classified personnel file declassified in 1998 includes a 1946 letter to his commanding officer requesting transfer away from ammunition development.
I can no longer contribute to weapons designed to cause such suffering regardless of military necessity.
Staff Sergeant Robert Henshaw dies on Okinawa May 18th, 1945, killed by a Japanese sniper.
He’s credited with 47 confirmed kills using M27 ammunition during the campaign.
His last letter home, written May 15th, 1945, includes a passage his family doesn’t understand until after declassification.
We have ammunition that does terrible things.
effective but terrible.
I pray this war ends before we become the things we’re fighting against.
The 1974 433,000 rounds of M27 ammunition produced during the war represent 187433,000 decisions to prioritize American lives over enemy suffering.
Those decisions saved an estimated $15,000, 20,000 American casualties based on comparative analysis of engagement outcomes.
They also created a moral legacy the Pentagon struggled with for four decades of classification and ultimately rejected for future use.
Veterans who used M27 ammunition rarely discussed it even after declassification.
The combination of classified secrecy and moral ambiguity created a conspiracy of silence that persisted until the 1990s.
When they did speak, most expressed the same conflicted view, necessary but haunting, effective but terrible, justified but unforgettable.
The M27 incendiary cartridge represents one of the most effective and controversial weapons in American military history.
It saved thousands of American lives.
It caused suffering that troubled even hardened combat veterans.
It remained classified longer than the atomic bomb project.
Most importantly, it reminds us that the men who fought our wars carried burdens we’ll never fully understand.
Burdens measured not just in physical scars, but in moral complexity and psychological weight.
These stories matter.
The innovation, the sacrifice, the moral struggles of the men who served deserve to be remembered and understood, not buried in classified archives and forgotten history.
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Where are you watching from? Did any family members serve in the Pacific? What other World War II innovations should we cover? Your engagement keeps these stories alive and honors the memory of those who served.
Remember Corporal Mitchell watching those men burn and knowing it saved his brother’s lives.
Remember Theodore Halpern, brilliant enough to create the weapon, but moral enough to question it.
Remember those 187 million rounds that saved Americans and haunted them at the same time? They carried this burden so we don’t have to.
The least we can do is
