US 105mm M60 HD Chemical Projectile – NFC Ordnance Training System

US 105mm M60 HD Chemical Projectile

Overview

The 105mm M60 HD Chemical Projectile is a chemical artillery round designed to deliver the vesicant (blister) agent HD (Sulfur Mustard, commonly called “Mustard Gas”) against enemy forces. Unlike the nerve agent variants in the M60 family, the HD-filled projectile is a persistent chemical weapon intended to create long-lasting contamination that denies terrain to enemy forces for extended periods. Sulfur mustard is one of the oldest chemical warfare agents, first used in World War I, and remains one of the most produced chemical weapons in history due to its effectiveness as a casualty-producing and area-denial agent. The M60 HD represents the Cold War-era U.S. artillery delivery system for this classic chemical agent. Understanding this munition is essential for EOD specialists, chemical demilitarization personnel, and humanitarian organizations working in areas where legacy chemical stockpiles may exist.

SAFETY WARNING: HD (Sulfur Mustard) is a highly toxic blister agent causing severe chemical burns to skin, eyes, and respiratory system. Effects may be delayed for hours, meaning exposure may occur without immediate symptoms. Any suspected chemical munition must be treated with extreme caution. DO NOT approach, handle, or disturb suspected chemical ordnance. Evacuate the area and contact qualified military chemical warfare/EOD specialists immediately.

Country/Bloc of Origin

Country: United States of America
Development Period: 1950s-1960s (projectile design); mustard agent dates to WWI era
Production Period: Cold War era stockpile production
Service Status: Declared obsolete; subject to Chemical Weapons Convention destruction requirements
Historical Note: Mustard agent was first used by Germany in 1917 and subsequently produced by most major military powers

Ordnance Class

Type: Artillery projectile (chemical ammunition)
Primary Role: Delivery of persistent blister agent for area denial and casualty production
Agent Type: HD (Sulfur Mustard) – persistent vesicant/blister agent
Delivery Method: Fired from 105mm howitzers (M101, M102 series)
Category: Chemical weapon; prohibited under Chemical Weapons Convention (CWC)

Ordnance Family/Nomenclature

Official Designation

M60 HD – 105mm chemical projectile filled with blister agent HD (Sulfur Mustard)

Related Variants (Same Projectile Body)

M60 GB – Filled with nerve agent GB (Sarin)
M60 VX – Filled with nerve agent VX
M60 HT – Filled with HT (mustard-T mixture, lower freezing point variant)

Agent Designations

H – Levinstein mustard (impure, older production method)
HD – Distilled mustard (purified sulfur mustard)
HT – Mustard-T mixture (HD mixed with agent T for lower freezing point)
Chemical Name: Bis(2-chloroethyl) sulfide
CAS Number: 505-60-2

Historical Names

“Mustard Gas” (common misnomer – it’s actually a liquid)
“Yperite” (from Ypres, Belgium, site of first use)
“Yellow Cross” (German WWI marking)
“Lost” (German designation)

Chemical Weapons Convention Status

Prohibited: Manufacturing, stockpiling, and use prohibited under CWC (1997)
Schedule 1 Chemical: Highest restriction category
Destruction Required: All signatory nations required to destroy stockpiles

Hazards

Primary Hazard: HD (Sulfur Mustard) Blister Agent

HD Characteristics:

Oily liquid, colorless when pure; typically yellow to brown due to impurities
Distinctive odor described as garlic, horseradish, or mustard
Low volatility – evaporates slowly, creating persistent contamination
Heavy – sinks in water; may contaminate water sources for extended periods
Delayed effects – symptoms typically appear 2-24 hours after exposure

Toxicity:

LCt50 (inhalation): Approximately 1,500 mg·min/m³
LD50 (skin): Approximately 100 mg/kg
Eye exposure threshold: Extremely low; ~12 mg·min/m³ can cause injury
Less acutely lethal than nerve agents but causes severe casualties and long-term injury

Routes of Exposure

Skin Contact: Primary route; liquid or vapor penetrates skin
Eye Exposure: Extremely sensitive; vapor causes injury at very low concentrations
Inhalation: Damages respiratory tract; can be lethal at high concentrations
Ingestion: Causes severe internal damage

Delayed Symptom Onset

CRITICAL: Unlike most toxic exposures, mustard symptoms are typically delayed:

No immediate pain or irritation at time of exposure
Symptoms appear 2-24 hours after exposure (typically 4-8 hours)
By the time symptoms appear, tissue damage has already occurred
This delay means victims may not recognize exposure and continue to contaminate themselves/others

Symptoms of Exposure

Eyes (most sensitive):

Irritation, gritty sensation
Severe conjunctivitis
Corneal damage and potential blindness

Skin:

Erythema (redness) progressing to vesication (blisters)
Large fluid-filled blisters, especially in moist areas (armpits, groin)
Deep chemical burns
Delayed healing; scarring

Respiratory:

Nasal irritation and discharge
Hoarseness, cough
Severe cases: airway damage, potentially fatal

Systemic:

Bone marrow suppression (delayed effect)
Immune system damage
Increased cancer risk (long-term)

Persistence and Environmental Hazards

Ground Contamination: Liquid HD persists for days to weeks depending on temperature and soil type
Cold Weather: Persistence increases dramatically; can remain hazardous for months
Water Contamination: HD sinks and can contaminate water sources long-term
Enclosed Spaces: Vapor accumulation in buildings, vehicles, bunkers
Thickened Variants: Some mustard formulations include thickeners that increase persistence further

Ordnance-Specific Hazards

Bursting Charge: Contains explosive to rupture projectile
Fuze Hazards: Point-detonating fuze presents explosive hazard
Leakage: Aged munitions may leak HD through corroded body or seals
Crystallization: HD may crystallize at low temperatures, especially around seals
Degradation Products: May form toxic degradation products over time

UXO/Chemical Ordnance Considerations

Aged Munitions: Corrosion increases leakage risk
Environmental Contamination: Leaked HD contaminates soil around munition
Dual Hazard: Explosive and chemical hazards simultaneously
Protective Equipment Required: Level A or military MOPP-4 for any approach
Decontamination Required: Personnel and equipment must be decontaminated after exposure

Immediate Action (Suspected Exposure)

Remove from contaminated area immediately
Remove and bag all contaminated clothing
Decontaminate skin with large amounts of water (or 0.5% bleach solution if available)
Do NOT scrub – may force agent into skin
Flush eyes with water for at least 15-20 minutes
Seek immediate medical attention
Note: No specific antidote exists; treatment is supportive

Key Identification Features

Dimensions

Length: Approximately 400mm (15.7 inches) without fuze
Diameter: 105mm (4.13 inches)
Weight: Approximately 18 kg (39.7 lbs) complete

Color Scheme and Markings

Standard Chemical Ammunition Marking:

Body Color: Gray
Band: Green band (indicates chemical agent fill)
Stenciling: Yellow markings

Specific Markings:

“HD” or “MUSTARD” stenciled in yellow
“GAS” marking
“BLISTER” may appear on some variants
Lot number and fill date
Manufacturer codes

Warning Signs of Leakage:

Oily residue (yellowish to brown)
Garlic/mustard odor
Crystalline deposits around seals
Discoloration of projectile body
Dead vegetation in vicinity

Distinctive Features

Gray Body: Standard for chemical ammunition
Green Band: Indicates chemical fill (same as nerve agent variants)
Fill Plug: Visible on body where agent was loaded
Weight: Similar to other M60 variants

Comparison with M60 Nerve Agent Variants

Feature	M60 HD	M60 GB	M60 VX
Body Color	Gray	Gray	Gray
Band	Green	Green	Green
Marking	Yellow “HD”	Yellow “GB”	Yellow “VX”
Agent Type	Blister	Nerve	Nerve
Persistence	High	Low	High
Primary Route	Skin	Inhalation	Contact

CRITICAL: Visual identification is identical for M60 HD, GB, and VX except for stenciled designations. Weathered or corroded rounds may have illegible markings. Treat any gray projectile with green band as potentially the most hazardous type until positively identified by specialists.

Material Composition

Body: Steel
Rotating Band: Copper or gilding metal
Fill: HD (Sulfur Mustard)
Burster: TNT or similar explosive
Fuze Well: Threaded steel

Fuzing Mechanisms

Compatible Fuzes

M557 Point-Detonating Fuze – Standard fuze; superquick or delay options
M572 Point-Detonating Fuze – Alternative
Standard 105mm PD fuzes compatible with chemical rounds

Functioning

The fuze functions identically to other M60 variants:

Impact: Fuze nose strikes target
Initiation: Firing pin activates detonator
Detonation: Burster charge fires
Dispersal: Projectile ruptures, spreading agent as droplets and aerosol

Arming Sequence

Bore Safety: Fuze remains safe until projectile clears tube
Setback Arming: Acceleration forces during firing
Spin Arming: Rotation from rifling completes arming
Armed State: Full arming achieved at safe distance

Superquick vs. Delay

Superquick: Immediate detonation maximizes agent dispersal as aerosol
Delay: Brief penetration creates more concentrated ground contamination

Safety Features

Standard artillery fuze safety features:

Interrupter mechanisms
Bore-safe design
Multi-point arming requirements

UXO Considerations

Assume fuze is armed and sensitive
Impact damage may have compromised fuze components
Age degradation of fuze mechanisms possible
Chemical hazard complicates any render-safe approach

History of Development and Use

Origins of Sulfur Mustard

Sulfur mustard was first synthesized in the 1820s, but its military potential wasn’t exploited until World War I. German forces first employed mustard agent at Ypres, Belgium, in July 1917. It rapidly became the most effective chemical weapon of the war, causing more chemical casualties than all other agents combined.

WWI Experience

Mustard proved devastating because:

Delayed action meant soldiers didn’t immediately recognize exposure
Persistence contaminated terrain, equipment, and shelters
Multiple effects caused casualties through skin, eye, and respiratory injury
Low lethality but high incapacitation overwhelmed medical systems
Psychological effect was profound; fear of gas attacks affected morale

By war’s end, mustard had caused an estimated 400,000+ casualties among all belligerents.

Interwar and WWII Period

Most major powers stockpiled mustard after WWI
Used by Italy in Ethiopia (1935-36)
Used by Japan in China (1930s-40s)
Stockpiled by all major WWII powers but not used in that conflict
U.S. maintained significant mustard stockpiles throughout

Cold War Stockpiling

The U.S. continued producing and stockpiling mustard agent through the Cold War:

Retained as retaliatory capability
Valued for its area-denial characteristics
HD considered complementary to nerve agents (different tactical uses)
M60 HD provided 105mm artillery delivery capability

Storage Sites

U.S. mustard munitions were stockpiled at various depots including:

Tooele Army Depot, Utah
Anniston Army Depot, Alabama
Deseret Chemical Depot, Utah
Johnston Atoll (Pacific)
Various other continental and overseas locations

Chemical Weapons Convention

CWC (1997) required destruction of all chemical weapons
Mustard represents a significant portion of most nations’ chemical stockpiles
Destruction has been challenging due to quantities and safety requirements
U.S. destruction ongoing at dedicated facilities

Current Status

Destruction Ongoing: Majority destroyed; remaining stocks scheduled for elimination
Legacy Contamination: Former production and storage sites may have environmental contamination
Sea-Dumped Munitions: Historical ocean disposal creates ongoing risks to fishermen and coastal areas
International Concern: Some non-signatory or non-compliant states may retain mustard stocks
Recent Use: Mustard has been used in recent conflicts (Syria, Iraq) despite prohibition

Notable Post-CWC Incidents

Despite the ban, mustard agent has appeared in recent conflicts:

Reports of ISIS use in Iraq/Syria (2014-2017)
Syrian government accused of mustard use
These incidents demonstrate the continued relevance of HD recognition for EOD/humanitarian personnel

Technical Specifications

Specification	Detail
Caliber	105mm
Projectile Length	~400mm (15.7 in) without fuze
Weight (Complete)	~18 kg (39.7 lbs)
Agent Fill	HD (Sulfur Mustard)
Fill Weight	Approximately 1.5 kg (3.3 lbs)
Burster Charge	TNT, ~340g
Muzzle Velocity	Variable by propelling charge
Maximum Range	~11,000m (12,000 yds)

Agent Specifications (HD/Sulfur Mustard)

Property	Value
Chemical Name	Bis(2-chloroethyl) sulfide
Molecular Weight	159.08 g/mol
Physical State	Oily liquid
Color	Colorless (pure) to yellow-brown (impure)
Odor	Garlic, horseradish, mustard
Vapor Pressure	0.072 mmHg at 20°C (low)
Freezing Point	14.4°C (57.9°F)
Persistence	Days to weeks (temperature dependent)
Solubility	Slightly soluble in water; soluble in oils

Persistence Characteristics

Conditions	Approximate Persistence
Hot, sunny, windy	1-2 days
Moderate conditions	3-7 days
Cool, calm	1-2 weeks
Cold, winter	Weeks to months
Frozen ground	Months

Contamination Area

A single M60 HD projectile can contaminate:

Lethal dosage area: ~50-100 m² depending on conditions
Casualty area: Several hundred m²
Detection/hazard area: Larger, dependent on vapor spread

Frequently Asked Questions

Q: Why was sulfur mustard called “mustard gas” when it’s actually a liquid? A: The term “gas” became common during WWI because chemical weapons were generically called “gases” regardless of their actual physical state. Mustard is actually an oily liquid at normal temperatures. When dispersed by artillery burst, it forms droplets and aerosol, with only slow vapor evaporation. The “mustard” name comes from its characteristic odor, which some describe as similar to mustard, garlic, or horseradish. Despite the misnomer, the term “mustard gas” remains widely used in popular and even some military contexts.

Q: How does the delayed action of mustard make it more dangerous than agents with immediate effects? A: The 2-24 hour delay between exposure and symptom onset creates several tactical and medical problems: (1) Continued exposure – victims don’t realize they’re contaminated and continue operating in contaminated areas; (2) Secondary contamination – contaminated personnel spread agent to others, equipment, and medical facilities before symptoms appear; (3) Irreversible damage – by the time symptoms appear, cellular damage has already occurred and cannot be reversed by treatment; (4) Psychological impact – soldiers never know if they’ve been exposed until hours later, creating persistent anxiety; (5) Medical overwhelm – mass casualties appearing simultaneously hours after attack strain medical resources. For EOD/first responders, this means potential exposure may not be immediately apparent, requiring strict decontamination protocols even without observed symptoms.

Q: What makes mustard agent “persistent” compared to “non-persistent” agents like GB (Sarin)? A: Persistence is determined by volatility – how quickly an agent evaporates. Mustard has very low vapor pressure (0.072 mmHg at 20°C) compared to GB (2.1 mmHg), meaning mustard evaporates roughly 30 times more slowly. This translates to: (1) Ground contamination lasting days to weeks for mustard versus hours for GB; (2) Equipment contamination remaining hazardous until actively decontaminated; (3) Area denial capability – mustard creates terrain that’s dangerous to occupy for extended periods. Tactically, mustard was used for defensive barriers, route denial, and slowing enemy operations, while non-persistent agents like GB were intended for offensive use where friendly forces would soon occupy the area.

Q: How can EOD or first responder personnel detect mustard contamination in the field? A: Several detection methods exist: (1) Odor – mustard has a characteristic garlic/horseradish smell, but odor threshold is higher than hazardous concentration, so absence of smell doesn’t mean safety; (2) M8 Detection Paper – turns red in contact with blister agents; (3) M9 Detection Paper – adhesive paper worn on clothing that changes color; (4) M256 Detection Kit – provides more specific identification; (5) CAM (Chemical Agent Monitor) – electronic detector; (6) Visual indicators – oily droplets, dead vegetation, discolored surfaces. However, personnel should never rely on detection to determine safety – always assume contamination when chemical munitions are suspected and use full protective equipment.

Q: Why is mustard still considered militarily relevant when nerve agents are more lethal? A: Mustard remains relevant for several reasons: (1) Casualty production – while less lethal, mustard produces massive numbers of casualties requiring medical evacuation and treatment, straining logistics; (2) Area denial – persistent contamination denies terrain, routes, and facilities for extended periods; (3) Psychological impact – fear of blistering injuries has profound morale effects; (4) Simplicity – mustard is relatively simple to produce compared to nerve agents; (5) Protective equipment degradation – prolonged operations in MOPP gear degrades combat effectiveness; (6) Decontamination burden – contaminated equipment must be decontaminated or destroyed, creating logistics problems. Nerve agents may be more lethal per kilogram, but mustard’s persistence and casualty-producing capacity make it a different but complementary threat.

Q: What decontamination methods are effective against mustard agent? A: Effective decontamination approaches include: (1) Physical removal – water washing removes liquid agent before it penetrates; must be done quickly after exposure; (2) Oxidizing bleach – 5% hypochlorite solution deactivates mustard through oxidation; (3) DS2 (Decontaminating Solution 2) – military decontaminant effective against mustard; (4) Fuller’s earth/flour – absorbs liquid agent from surfaces; (5) Weathering – eventually, exposure to air and sunlight degrades mustard, but this takes days to weeks. For personnel decontamination, immediate removal of clothing and water flush is critical; scrubbing should be avoided as it may force agent into skin. There is no antidote – medical treatment is supportive only, focused on treating burns and preventing infection.

Q: How does the M60 HD differ in tactical employment from the M60 GB or M60 VX? A: The tactical employment differs based on persistence and effect: M60 GB (non-persistent nerve agent) – used for immediate casualties on objectives about to be assaulted; vapor dissipates allowing friendly occupation within hours. M60 HD (persistent blister) – used for area denial, contaminating routes, assembly areas, or defensive positions where extended denial is desired; not used on terrain friendly forces will soon occupy. M60 VX (persistent nerve agent) – combines the area denial capability of mustard with the higher lethality of nerve agents; used when long-term contamination with lethal effect is desired. In defensive planning, mustard would be employed along flanks and approaches, while GB might be used for immediate counterattack support.

Q: What are the unique challenges of disposing of aged mustard munitions compared to nerve agent munitions? A: Mustard munitions present several unique destruction challenges: (1) Polymerization – aged mustard often forms a thick, tar-like residue (“heel”) in containers that’s difficult to remove; (2) Freezing point – HD freezes at 14.4°C, so winter operations require heating; some facilities had issues with frozen agent; (3) Large quantities – mustard was produced in greater quantities than nerve agents, meaning more munitions to destroy; (4) Corrosion interaction – mustard reacts with steel, creating crusty deposits that complicate handling; (5) Lower volatility – requires higher temperatures for incineration compared to GB. The Chemical Stockpile Emergency Preparedness Program (CSEPP) developed specialized procedures for mustard munitions, including hot water washout of containers before final destruction.

Q: What environmental and health legacy exists from historical mustard production and storage? A: Significant legacy contamination issues exist: (1) Production sites – Former manufacturing facilities like Edgewood Arsenal have required extensive remediation; (2) Storage sites – Decades of storage led to leaking munitions contaminating soil; (3) Sea-dumped munitions – After WWII, large quantities of chemical munitions including mustard were dumped at sea; these occasionally wash ashore or are recovered in fishing nets; (4) Testing areas – Proving grounds where mustard was tested may have residual contamination; (5) Burial sites – Some chemical weapons were buried, creating unknown hazards. Long-term health effects on production workers and surrounding communities have been documented, including elevated cancer rates. These legacy issues drive continued investment in detection, remediation, and medical surveillance.

SAFETY NOTICE: This lesson is intended for educational and training purposes. All ordnance should be considered dangerous until proven safe by qualified personnel. Unexploded ordnance should never be handled by untrained individuals—report findings to military or law enforcement authorities.