US ABC-M25A2 Riot Control Grenade
1. Overview
The ABC-M25A2 is a United States military bursting-type riot control hand grenade designed to disperse riot control agents through the instantaneous rupture of its grenade body. Unlike the burning-type M7 series, the M25A2 uses a detonator to burst its spherical plastic body, instantly dispersing the chemical agent filler as a powder cloud. The M25A2 is an improved version of the M25A1 and can be filled with CS1, CN1, or DM1 riot control agents, as well as the T1 simulant agent for training. The CS1-filled variant is the most commonly encountered. The M25A2 offers advantages over burning-type grenades in certain tactical situations, particularly where fire hazards preclude the use of pyrotechnic grenades.
⚠️ SAFETY WARNING: All ordnance should be considered dangerous until proven safe by qualified personnel. Bursting-type grenades contain explosive detonators and produce fragments. Friendly forces should don protective masks before throwing this grenade. This information is for educational and identification training purposes only.
2. Country/Bloc of Origin
- Country of Origin: United States of America
- Period of Development: M25 series originated in the 1950s; M25A2 variant developed as an improved version with upgraded body construction, with CS1-filled variants entering service during the 1960s
- Manufacturer: Various US defense contractors
3. Ordnance Class
- Type of Weapon: Hand grenade — chemical (riot control)
- Primary Role: Riot control, crowd dispersal, area denial, training simulation of casualty agents
- Delivery Method: Hand-thrown by individual soldier
- Grenade Category: Chemical grenade — bursting type
4. Ordnance Family / Nomenclature
- Official Designation: Grenade, Hand, Riot Control, CS1, ABC-M25A2 (CS1-filled variant)
- Also Known As: M25A2 Riot Control Grenade
- Agent Variants Loaded:
- CS1 (most common) — Grenade, Hand, Riot, CS1, ABC-M25A2
- CN1 — Grenade, Hand, Riot, CN1, ABC-M25A2
- DM1 — Grenade, Hand, Riot, DM1, ABC-M25A2 (also designated E21/E21R1 during development)
- T1 (simulant) — for training
- Related Variants:
- M25 — Original variant; fiberglass body; filled with CN agent only
- ABC-M25A1 — Improved body construction; filled with CN1
- ABC-M25A2 — Further improved body (compressed fiber or plastic); multiple agent options
- Related Items:
- EX 1 Mod 0 — Modified M25 series for the US Navy’s Target Illumination and Recovery Aid (TIARA) program; filled with PB-155 chemiluminescent filler for nighttime target marking
- Experimental Rifle Launching: An adapter to allow the M25 series to be rifle-launched was tested but not adopted
- Current Status: Listed as obsolete in US Army documentation, but may still be encountered in legacy stocks
5. Hazards
- Detonator Hazard: Unlike burning-type grenades, the M25A2 contains an explosive detonator in the integral fuze assembly. This detonator is a high-explosive component that ruptures the grenade body.
- Fragment Hazard: The visible cloud radius (agent burst) is approximately 5 meters (16 feet), but grenade body fragments may project as far as 25 meters (82 feet). This is a significantly greater fragment hazard than burning-type riot control grenades.
- Chemical Agent Effects (CS1 variant):
- Powerful lachrymatory effect (intense tearing)
- Irritating to upper respiratory passages causing coughing, difficulty breathing, and chest tightness
- Heavy concentrations cause nausea and vomiting
- Onset of incapacitation: 15–30 seconds
- Duration: 30 minutes to several hours depending on dosage concentration (longer than burning-type CS grenades due to the powder burst dispersal method)
- CS is more persistent and produces more severe reactions than CN
- DM1 Variant Hazard: The DM1 (adamsite / diphenylaminechlorarsine) variant is a vomiting agent that causes a burning sensation in the nose and throat, heavy chest tightness, and severe nausea. DM is significantly more debilitating than CS and has arsenic-containing compounds.
- No Fire Hazard: Unlike burning-type grenades, the M25A2 does not produce sustained flame or high heat. It can be used in environments where fire hazard is a concern.
- Protective Mask Required: Friendly forces MUST don protective masks before employing this grenade.
- UXO Considerations: A dud M25A2 contains a live explosive detonator in addition to chemical agent. The detonator makes unexploded M25A2 grenades more hazardous than dud burning-type grenades. The fuze mechanism may be partially armed.
6. Key Identification Features
- Body: Spherical; constructed from two plastic (or compressed fiber) hemispheres cemented together
- Body Construction: The two hemispheres form a burster well and slider housing when joined
- Color/Markings: Gray body with red band and red markings (standard US riot control color scheme). Agent type (CS1, CN1, DM1, or T1) will be stenciled on the body.
- Weight: Approximately 8 ounces (227 g) — significantly lighter than the M7 series (15.5 oz)
- Fuze: Integral fuze (pyrotechnic delay-detonating type) — built into the grenade body, not a separate attachable fuze like the M201A1
- Safety Pin: Pull ring with safety pin
- Safety Clip: None
- Size: Approximately baseball-sized spherical body
- Distinction from M25/M25A1: The three M25 variants are essentially identical in external appearance, differing primarily in body construction materials (fiberglass → compressed fiber → plastic). Markings and body material are the means of differentiation.
7. Fuzing Mechanisms
- Fuze Type: Integral pyrotechnic delay-detonating fuze (built into the grenade body)
- Fuze Components:
- Arming sleeve
- Arming pin (safety pin with pull ring)
- Firing spring
- Slider assembly
- Firing pin
- Slider Assembly Contains:
- Primer
- Pyrotechnic delay column
- Detonator (explosive)
- Arming and Functioning Sequence:
- Soldier grips the grenade, holding the arming sleeve against the body
- Safety pin is pulled, releasing the arming pin
- Upon release (throwing), the arming sleeve separates
- The firing spring drives the slider assembly into alignment with the firing pin
- The firing pin strikes the primer in the slider assembly
- The primer ignites the pyrotechnic delay column
- After delay (approximately 1.5–3 seconds), the delay column fires the detonator
- The detonator explodes, rupturing the plastic grenade body and dispersing the CS1 (or other agent) filler as an instantaneous powder cloud
- Key Design Feature: The fuze is integral to the grenade body — it cannot be removed or replaced separately. This is a significant design difference from the M7 series, which uses the detachable M201A1 fuze.
- All fillers are mixed with silica aerogel for increased dissemination efficiency upon burst
8. History of Development and Use
The M25 series was developed in the 1950s to provide a bursting-type alternative to the burning-type riot control grenades (M6/M7 series) then in service. The bursting mechanism offered several tactical advantages: instantaneous agent dispersal rather than a gradual 15–35 second burn, no fire hazard, and a more compact effective cloud.
The original M25 used a fiberglass body and was filled only with CN agent. The M25A1 improved the body construction and transitioned to CN1 filler (CN mixed with silica aerogel for better dissemination). The M25A2 represented a further improvement in body construction, using compressed fiber or plastic, and expanded the range of agent fills to include CS1, CN1, DM1, and the T1 training simulant.
The CS1-filled M25A2 became the most commonly issued variant as CS replaced CN as the standard military riot control agent. The DM1 variant was developed separately under the experimental designations E21 and E21R1 before being standardized as an M25A2 sub-variant.
An interesting footnote in the M25 series history is the US Navy’s adaptation of a modified M25 grenade (designated EX 1 Mod 0) for the Target Illumination and Recovery Aid (TIARA) program in the 1960s. This variant was filled with PB-155 chemiluminescent filler produced by DuPont Chemical Company, intended to scatter non-toxic glowing material to mark targets at night.
The ABC-M25A2 is listed as obsolete in current US Army inventory documentation. It has been largely superseded by newer less-lethal munitions. However, legacy stocks may still exist in some inventories, and the grenade may be encountered in UXO contexts, particularly at former US military installations and in countries that received US military aid during the Cold War.
9. Technical Specifications
| Specification | Detail |
|---|---|
| Designation | Grenade, Hand, Riot Control, CS1, ABC-M25A2 |
| Type | Chemical — Bursting |
| Primary Agent (most common) | CS1 (CS with silica aerogel) |
| Available Fills | CS1, CN1, DM1, T1 (simulant) |
| Filler Additive | Silica aerogel (all variants) for improved dissemination |
| Total Weight | ~8 oz (227 g) |
| Body Material | Compressed fiber or plastic (two hemispheres) |
| Body Shape | Spherical |
| Fuze | Integral pyrotechnic delay-detonating |
| Fuze Delay | ~1.5–3 seconds |
| Safety Clip | None |
| Throwing Range | ~50 meters (average soldier) |
| Burst Radius (visible cloud) | ~5 m (16 ft) |
| Fragment Hazard Distance | Up to 25 m (82 ft) |
| Color/Markings | Gray body, red band, red markings |
| Agent Onset | 15–30 seconds |
| Agent Duration | 30 minutes to several hours (dosage dependent) |
| Current Status | Obsolete (legacy stocks may exist) |
| Reference | FM 23-30 / TC 3-23.30 |
10. Frequently Asked Questions
Q: What is the key operational advantage of the M25A2 bursting-type grenade over the M7 series burning-type? A: The M25A2 disperses its agent charge instantaneously upon the detonator functioning, creating an immediate cloud of CS1 powder. This eliminates the 15–35 second build-up time required by burning-type grenades. Additionally, the M25A2 does not produce fire, making it suitable for use in environments where fire hazards preclude the use of pyrotechnic grenades (near fuel, ammunition, in dry vegetation, etc.).
Q: Why does the M25A2 have a greater fragment hazard than the M7 series? A: The M25A2 uses an explosive detonator to burst its plastic body, projecting body fragments up to 25 meters. The M7 series uses a burning process — while the M7’s sheet metal body can produce minor fragments if the grenade malfunctions, it does not have a deliberate fragmentation mechanism. The M25A2’s fragment hazard is an important safety consideration that distinguishes it from the seemingly less hazardous burning-type grenades.
Q: Why is the M25A2’s agent effect duration longer than the M7 series? A: The M25A2 disperses CS1 as a fine powder burst mixed with silica aerogel, which enhances airborne suspension time and surface adhesion. This powder can persist on surfaces and become resuspended by movement or air currents for 30 minutes to several hours. The M7 series generates CS as smoke from a burning process, which dissipates more quickly once the burn is complete.
Q: What makes the DM1-filled M25A2 variant particularly hazardous? A: DM (adamsite / diphenylaminechlorarsine) is a significantly more debilitating agent than CS. It causes intense burning in the nose and throat, heavy chest tightness, severe nausea and uncontrollable vomiting, and temporary incapacitation. DM contains arsenic compounds and has a narrower safety margin than CS. The DM1-filled M25A2 should be treated with particular caution and is governed by more restrictive rules of engagement than CS variants.
Q: How do you distinguish the M25A2 from a standard fragmentation grenade in the field? A: The M25A2 is spherical (similar in size to a baseball) with a smooth plastic or compressed fiber body in gray with red markings. Fragmentation grenades (such as the M67) have a steel body with a distinctive rough or scored surface, are heavier, and bear olive drab coloring with yellow markings. The M25A2’s plastic construction, light weight (8 oz vs. 14 oz for the M67), and red markings should clearly distinguish it, but the spherical shape can cause momentary confusion in stress situations.
Q: Why is the M25A2 listed as obsolete? A: The M25A2 has been superseded by newer less-lethal munitions that offer improved safety, effectiveness, and agent formulations. However, “obsolete” in military inventory terms does not mean the items no longer exist — legacy stocks may remain in warehouses, forward-positioned stockpiles, or in the inventories of countries that received US military assistance. UXO and clearance personnel should be familiar with the M25A2 as it may be encountered in field contexts.
Q: Can the M25A2’s integral fuze be disarmed? A: The M25A2’s fuze is built into the grenade body and is not designed to be disarmed in the field. Once the safety pin is removed and the grenade is thrown, the functioning sequence is irreversible. An unexploded M25A2 with its safety pin removed should be treated as an armed device with a live explosive detonator. Only qualified EOD personnel should approach dud M25A2 grenades. Even with the safety pin in place, the presence of an explosive detonator makes the M25A2 more hazardous than burning-type grenades during storage and handling.