US M228 Grenade Fuze

1. Overview

The M228 Grenade Fuze is a U.S. military pyrotechnic delay-igniting fuze used as a training practice fuze (TPF). It is employed in conjunction with the M69 Practice Hand Grenade body to provide realistic training for the M67 Fragmentation Hand Grenade, which uses the live M213 fuze. The M228 replicates the handling, arming, and functioning characteristics of the M213 but produces only a small puff of smoke and an audible report upon functioning rather than a lethal detonation, allowing safe and realistic grenade training.

⚠ SAFETY WARNING: All ordnance — including training and practice items — should be considered dangerous until rendered safe by qualified personnel. The M228 fuze contains energetic materials (primer, pyrotechnic delay composition) that can cause injury. Report all suspected ordnance to military or law enforcement authorities. This information is for educational and identification training purposes only.

2. Country/Bloc of Origin

  • Country: United States of America
  • Developed By: U.S. Army Armaments Center (Picatinny Arsenal, New Jersey)
  • Service Period: In service from standardization (originally designated XM228) through the present day
  • Current Use: Active U.S. military training fuze

3. Ordnance Class

  • Type: Grenade fuze (training/practice)
  • Primary Role: Training practice fuze for realistic hand grenade training
  • Associated Grenade Body: M69 Practice Hand Grenade (simulates the M67 Fragmentation Hand Grenade)
  • Live Counterpart: M213 Grenade Fuze (used in the M67 Fragmentation Hand Grenade)

4. Ordnance Family / Nomenclature

  • Official Designation: Fuze, Grenade, M228 (formerly XM228)
  • DODIC: GG44 (practice hand grenade fuze); GG45 (practice hand grenade body)
  • Related Fuzes:
    • M213 — Live fragmentation grenade fuze (M67); contains detonator and booster; 4.0–5.5 second delay
    • M228 — Training practice fuze; same primer and delay as M213 but terminates in an igniter charge (smoke/report) rather than a detonator
    • M201/M201A1 — Pyrotechnic delay-igniting fuze used with smoke grenades (M18 series, AN-M8, etc.); 1.0–2.3 second delay
    • M206/M206A2 — Pyrotechnic delay fuze used with the Mk3A2 offensive grenade; 5-second delay
    • M240 TPF — Modified M201A1 training practice fuze; 1.0–2.3 second delay; used with practice smoke/non-lethal grenades
  • Thread Pattern: Standard U.S. grenade fuze well thread

5. Hazards

  • Primary Hazard: The M228 contains energetic materials including a percussion primer, a pyrotechnic delay column, and an igniter charge. While not designed to produce lethal effects, the fuze can cause burns, eye injuries, and minor fragmentation injuries if functioning in close proximity to personnel.
  • Output: Small puff of smoke and an audible report — sufficient to indicate functioning but not lethal
  • Handling Hazards:
    • The primer is sensitive to impact — dropping the fuze onto a hard surface with sufficient force could initiate the primer
    • The pyrotechnic delay column contains hazardous materials including (in legacy versions) hexavalent chromium, lead chromate, barium chromate, and potassium perchlorate
    • Modern “green” replacement compositions are in development under ESTCP WP20-5045 to eliminate these toxic materials
  • UXO Considerations:
    • Unexpended M228 fuzes and M69 practice grenades should be treated as hazardous ordnance
    • Failed fuzes (initiated but did not function completely) may contain burning or partially burned pyrotechnic material
    • The M69 practice grenade body is reusable; only the fuze is single-use
  • Environmental/Health Hazard: Legacy M228 delay compositions contain toxic materials. The “Green M213/M228 Fuze” program is developing environmentally benign replacements.

6. Key Identification Features

  • Fuze Body Material: Zinc alloy (zamac)
  • Safety Lever Color: Blue with a brown tip at the end of the safety lever — this distinguishes the M228 training fuze from the olive drab lever of the live M213 fuze
  • Safety Clip: Present on current production models; older M228 models (pre-2007) may not have a safety clip
  • Confidence Clip: Present on grenades produced after 2007; the pull ring seats into the confidence clip for additional safety
  • Safety Pin: Steel safety pin with pull ring; split end has an angular spread or diamond crimp
  • Physical Dimensions: Same external dimensions and thread pattern as the M213 live fuze
  • Weight: Comparable to M213
  • Markings: Marked to indicate training/practice status
  • Distinctive Features:
    • The blue safety lever with brown tip is the primary visual identifier distinguishing the M228 from live fuzes
    • No detonator or booster — terminates in a black powder or pyrotechnic igniter charge
    • Produces a visible puff of smoke when functioning

7. Fuzing Mechanisms

  • Fuze Type: Pyrotechnic delay-igniting fuze (training practice)
  • Internal Components:
    • Percussion primer (M42 primer — same as M213 live fuze)
    • Pyrotechnic delay column (same composition as M213; Z-1 delay in legacy versions)
    • Igniter charge (black powder or pyrotechnic — produces smoke/report; replaces the detonator/booster of the M213)
  • Arming/Functioning Sequence:
    1. Release the safety clip (if equipped)
    2. Disengage the pull ring from the confidence clip (if equipped)
    3. Remove the safety pin by pulling the ring
    4. Hold the safety lever against the grenade body
    5. Throw the grenade — releasing the safety lever
    6. The spring-loaded striker assembly throws off the safety lever and impacts the percussion primer
    7. The primer ignites the pyrotechnic delay column
    8. The delay column burns for 4.0–5.5 seconds
    9. The delay composition initiates the igniter charge
    10. The igniter produces a small puff of smoke and an audible report (indicating function)
  • Delay Time: 4.0–5.5 seconds (same as M213 live fuze)
  • Safety Mechanisms:
    • Safety pin with pull ring
    • Safety clip (current production)
    • Confidence clip (post-2007 production)
    • Spring-loaded safety lever

8. History of Development and Use

The M228 was developed as the training companion to the M213 live fragmentation grenade fuze to provide soldiers with a realistic training experience that replicates the weight, handling, arming sequence, and timing of a live M67 grenade throw. The M228 shares the same percussion primer (M42) and the same pyrotechnic delay composition as the M213, ensuring that the delay timing (4.0–5.5 seconds) accurately simulates the live fuze.

The key difference is in the output: where the M213 terminates in a C70 detonator and booster charge that initiates the main explosive fill of the M67 grenade body, the M228 terminates in an igniter charge that produces only a puff of smoke and a report. The M69 practice grenade body is a reusable training item; only the M228 fuze is consumed during each training iteration.

Over the years, the M228 has undergone several safety improvements. Models produced before 1970 may lack safety clips entirely. The confidence clip was added to grenades produced after 2007, providing an additional layer of safety by securing the pull ring until the user deliberately disengages it.

Current modernization efforts focus on replacing the toxic materials in the M228’s pyrotechnic delay column. The legacy Z-1 delay composition and M42 primer contain hazardous materials including lead styphnate, lead azide, hexavalent chromium, barium chromate, and potassium perchlorate. The SERDP/ESTCP “Green M213/M228 Fuze” program (WP20-5045) is demonstrating environmentally benign alternatives including tungsten/manganese dioxide thermitic delay compositions and DBX-1 (Copper(I) 5-nitrotetrazolate) primer replacements.

9. Technical Specifications

ParameterValue
Fuze TypePyrotechnic delay-igniting (training practice)
Fuze Body MaterialZinc alloy (zamac)
Delay Time4.0–5.5 seconds
PrimerM42 percussion primer
Delay CompositionZ-1 (legacy); Mn/MnO₂ or W/MnO₂ (green replacement, in development)
OutputIgniter charge (smoke puff and audible report)
Safety LeverBlue with brown tip
Safety PinSteel with pull ring; angular spread or diamond crimp
Safety ClipYes (current production; not on pre-1970 models)
Confidence ClipYes (post-2007 production)
Thread PatternStandard U.S. grenade fuze well thread
Associated Grenade BodyM69 Practice Hand Grenade
Live CounterpartM213 Fuze / M67 Fragmentation Hand Grenade

10. Frequently Asked Questions

Q: What is the difference between the M228 and the M213 fuze? A: The M228 and M213 share the same percussion primer (M42), the same pyrotechnic delay composition, and the same delay time (4.0–5.5 seconds). The critical difference is in the output charge: the M213 contains a C70 detonator and booster that initiates the explosive fill of the M67 grenade, while the M228 contains only an igniter charge that produces a puff of smoke and an audible report. This makes the M228 safe for training use while replicating the timing and handling of the live fuze.

Q: Can the M228 cause injuries? A: Yes. Although designed as a training item, the M228 contains energetic materials that can cause burns, eye injuries, and minor fragmentation injuries at very close range. The percussion primer, pyrotechnic delay column, and igniter charge all contain pyrotechnic materials. Proper safety distances and protective equipment must be maintained during training.

Q: How can the M228 be visually distinguished from the live M213 fuze? A: The M228 features a blue safety lever with a brown tip, while the M213 live fuze has an olive drab safety lever marked “IMPACT.” This color coding is the primary visual indicator that distinguishes training from live fuzes. Personnel should always verify fuze type by checking the lever color and markings before handling.

Q: Why are older M228 fuzes potentially more hazardous than current production? A: Older M228 fuzes (pre-1970) may not have safety clips, and pre-2007 models lack confidence clips. These additional safety features reduce the risk of accidental initiation during handling and storage. Older fuzes rely solely on the safety pin and lever for safety, providing fewer layers of protection against inadvertent functioning.

Q: What is the “Green M213/M228 Fuze” program? A: This is a U.S. Department of Defense Environmental Security Technology Certification Program (ESTCP) initiative (WP20-5045) to replace the toxic materials in the M213 and M228 fuze firing trains with environmentally benign alternatives. The legacy compositions contain lead styphnate, lead azide, hexavalent chromium, barium chromate, and potassium perchlorate — all of which pose environmental and health risks during manufacturing, use, and disposal. Replacement candidates include tungsten/manganese dioxide delay compositions and DBX-1 primer replacements.

Q: Is the M69 practice grenade body reusable? A: Yes. The M69 practice grenade body is designed to be reused. After each training iteration, the spent M228 fuze is removed and replaced with a new M228 fuze. Soldiers must be properly trained in the fuze replacement procedure before training events. Instructions should be given prior to training.

Q: How does the M228 relate to the M240 training practice fuze? A: The M240 TPF is a modified M201A1 fuze used for training with non-lethal/smoke grenades. It has a much shorter delay (1.0–2.3 seconds) compared to the M228’s 4.0–5.5 seconds. The M240 features a blue safety lever with a brown band (not tip) and has both a primary safety pin (circular pull ring) and a secondary safety pin (triangular pull ring). Both are training fuzes but designed for different grenade types and applications.