US M2 Firing Device (Time Blasting Fuse Igniter, M2, Weatherproof)

Overview

The M2 Firing Device, officially designated the Igniter, Time Blasting Fuse, M2, Weatherproof, is a compact mechanical device developed by the United States during World War II to reliably ignite time blasting fuse (safety fuse) under adverse weather conditions. This device represented a significant improvement over the earlier M1 Fuse Lighter, offering enhanced weatherproofing capabilities including underwater functionality. The M2 became the standard fuse igniter for US military demolition operations from late WWII through subsequent conflicts.

Country/Bloc of Origin

  • Country of Origin: United States of America
  • Developing Organization: US Army Engineer Board, in collaboration with The A.C. Gilbert Company
  • Development Period: 1943
  • Manufacturing: Initial production by The A.C. Gilbert Company; subsequent contracts resulted in over 6 million units produced
  • International Use: Supplied to Allied forces during WWII; also provided to resistance movements through OSS channels

Ordnance Class

  • Type: Initiating Device / Fuse Igniter
  • Primary Role: Ignition of time blasting fuse (safety fuse) for demolition operations
  • Delivery Method: Hand-emplaced
  • Category: Demolition Accessory Equipment
  • Function: Provides a weatherproof, reliable method of igniting time blasting fuse without external flame sources

Ordnance Family/Nomenclature

Official Designations:

  • Igniter, Time Blasting Fuse, M2, Weatherproof
  • M2 Fuse Lighter (common name)

Related Variants:

  • M1 Fuse Lighter: Earlier, less weatherproof version; friction-type igniter
  • M60 Weatherproof Fuse Igniter: Post-WWII improved design with pull-friction mechanism
  • M81 Fuse Igniter: Modern replacement capable of initiating both time blasting fuse and shock tube

Common Names/Nicknames:

  • M2 Fuse Lighter
  • Weatherproof Fuse Igniter
  • Pull-Friction Igniter

NSN (Historical): Various NSNs assigned depending on packaging configuration

Hazards

Primary Hazards:

  • Flash/Flame Hazard: Produces a brief, intense flash and flame upon activation sufficient to ignite time blasting fuse
  • Minor Burn Hazard: Flash can cause minor burns if fingers are positioned near the ignition point during activation

Sensitivity Considerations:

  • Device requires deliberate mechanical action (pull) to function
  • Not sensitive to shock, vibration, or electromagnetic interference
  • Stable across a wide temperature range

Environmental Stability:

  • Designed for reliable function in wet conditions including rain, snow, and shallow underwater use
  • Waterproof construction prevents moisture intrusion
  • Extended storage may degrade internal components; inspection required before use of aged stock

Special Hazards:

  • Ignition element contains pyrotechnic composition; store away from flammable materials
  • Do not disassemble—internal components under spring tension

UXO Considerations:

  • Unfired M2 igniters are generally stable
  • If found with attached time blasting fuse or connected to explosive charges, treat as potentially hazardous
  • Report to EOD personnel for proper disposal

Key Identification Features

Dimensions:

  • Length: Approximately 2.5-3 inches (63-76mm)
  • Diameter: Approximately 0.5 inches (12.7mm)

Physical Characteristics:

  • Small, cylindrical brass or aluminum body
  • Split-ring pull mechanism at one end
  • Fuse crimping attachment at the opposite end
  • Knurled or ribbed grip surface for handling in wet conditions

Color and Markings:

  • Body Color: Olive drab or natural metal finish (brass/aluminum)
  • Markings: “M2” designation stamped on body; manufacturer markings and lot numbers present on some examples
  • Packaging Markings: Yellow band or text indicating pyrotechnic content

Distinctive Features:

  • Pull ring attached via split ring to internal pull wire
  • Crimping attachment designed to accept standard time blasting fuse
  • Waterproof seals at both ends
  • Smooth, streamlined profile compared to earlier M1 design

Material Composition:

  • Body: Brass or aluminum alloy
  • Pull mechanism: Steel wire with brass or nickel-plated pull ring
  • Seals: Rubber or synthetic waterproofing compounds
  • Ignition element: Pyrotechnic friction composition

Fuzing Mechanisms

Operating Principle: The M2 operates on a pull-friction ignition principle. A wire coated with friction-sensitive pyrotechnic material passes through a friction compound. When the pull ring is pulled sharply, the coated wire is drawn through the friction compound, generating sufficient heat to ignite the pyrotechnic element.

Activation Sequence:

  1. Preparation: Remove any protective cap from the fuse attachment end
  2. Fuse Attachment: Insert time blasting fuse into the crimping end; crimp securely
  3. Actuation: Grasp the igniter body firmly; pull the ring sharply with the other hand
  4. Ignition: Friction ignites the pyrotechnic composition, producing a flash that ignites the fuse

Safety Features:

  • Requires deliberate mechanical action to function
  • Pull force of several pounds required prevents accidental activation
  • No external safety pin—relies on secure grip and deliberate pull
  • Waterproof construction prevents moisture degradation of ignition element

No Self-Destruct Feature: Device does not self-neutralize; unfired igniters remain functional indefinitely if properly stored

Power Source: None required—entirely mechanical/pyrotechnic operation

History of Development and Use

Development Timeline:

  • 1941-1942: US Army identifies need for improved fuse igniter for wet conditions after M1 Fuse Lighter proves unreliable in Pacific theater operations
  • August 1943: A.C. Gilbert Company develops the M2 in collaboration with Mr. J.P. Roysdon of the Engineer Board
  • 1943: Initial production contract for 5,000 units awarded to A.C. Gilbert Company
  • 1943-1945: Production expands dramatically; over 6 million units manufactured by war’s end
  • Post-WWII: M2 remains in service; gradually supplemented and eventually replaced by M60 and M81 igniters

Key Historical Events:

  • The M2’s weatherproof design addressed critical deficiencies experienced during amphibious operations and jungle warfare in the Pacific
  • Became standard issue for US Army combat engineers, Navy underwater demolition teams, and OSS operatives
  • Supplied to Allied forces and resistance movements throughout Europe and Asia

Combat Use:

  • World War II: Extensive use in both Pacific and European theaters
  • Korean War: Standard fuse igniter for demolition operations
  • Vietnam War: Continued use alongside newer igniter designs
  • Employed by special operations forces for covert demolition missions

Current Status:

  • Obsolete for active US military use
  • Replaced by M60 and M81 Fuse Igniters
  • Encountered as collector’s items and in historical ordnance collections
  • May still be found in legacy ammunition stocks in some countries

Production Numbers:

  • Over 6 million units produced during WWII
  • Additional production during Korean War era

Impact on Doctrine:

  • Established the requirement for weatherproof ignition devices in military demolition kits
  • Influenced subsequent fuse igniter designs emphasizing reliability in adverse conditions

Technical Specifications

SpecificationDetails
LengthApproximately 2.5-3 inches (63-76mm)
DiameterApproximately 0.5 inches (12.7mm)
WeightApproximately 0.5-1 oz (14-28g)
Body MaterialBrass or aluminum alloy
Ignition ElementFriction-sensitive pyrotechnic composition
Activation Force3-8 pounds pull force
Operating Temperature Range-40°F to +150°F (-40°C to +65°C)
Waterproof RatingFunctional when wet; suitable for shallow underwater use
Shelf LifeExtended if properly stored in sealed containers
Compatible FuseStandard time blasting fuse (safety fuse), 0.2-inch diameter
Quantity-Distance Class1.4
Storage Compatibility GroupS
DOT ClassificationClass C Explosive

Frequently Asked Questions

Q: How does the M2 Firing Device differ from the earlier M1 Fuse Lighter? A: The M2 was specifically designed to address the M1’s shortcomings in wet conditions. The M2 features improved waterproof seals, a more robust ignition element protected from moisture, and the ability to function after immersion in water. The M2 can also ignite fuse underwater without producing a visible flash, making it more suitable for covert operations. The overall design is more streamlined and reliable than the M1.

Q: Can the M2 be used with modern shock tube (NONEL) systems? A: No. The M2 was designed exclusively for time blasting fuse (safety fuse). It cannot reliably initiate shock tube. For shock tube systems, the M81 Fuse Igniter or purpose-built shock tube initiators must be used. The M81 can initiate both time blasting fuse and shock tube, making it the preferred modern alternative.

Q: Why was pull-friction ignition chosen over other methods? A: Pull-friction ignition provides several advantages for field use: it requires no external power source, is highly reliable across temperature extremes, produces no noise during preparation, and allows the user to maintain a secure grip on the device during activation. The mechanical simplicity also meant lower manufacturing costs and higher production volumes during wartime.

Q: What safety precautions should be observed when using the M2? A: Always ensure the fuse is properly crimped before activation. Keep fingers clear of the ignition end. Pull the ring in a direction away from the body. Never look directly at the ignition point during activation. After activation, move away promptly as the time blasting fuse is burning. Never attempt to disassemble the device or reuse a misfired igniter.

Q: How accurate is the timing when using the M2 with time blasting fuse? A: The M2 itself does not provide timing—it simply ignites the time blasting fuse. Timing accuracy depends on the fuse used. Standard military time blasting fuse burns at approximately 40 seconds per foot (0.5 meters per minute). Environmental factors such as temperature and altitude can affect burn rate by ±10-15%.

Q: Were M2 Firing Devices used by special operations forces? A: Yes. The M2’s compact size, reliability, and underwater capability made it ideal for OSS operations during WWII. It was included in standard OSS demolition kits and provided to resistance movements in occupied Europe. The device’s ability to function without producing a visible flash when used underwater was particularly valued for clandestine maritime operations.

Q: How should M2 Firing Devices be stored? A: M2 igniters should be stored in their original sealed containers in a cool, dry environment. They should be kept away from heat sources, direct sunlight, and incompatible materials. Before use, inspect for corrosion, damaged seals, or other deterioration. Aged or damaged igniters should be disposed of through proper explosive ordnance disposal channels.

Q: What replaced the M2 in US military service? A: The M2 was gradually replaced by the M60 Weatherproof Fuse Igniter, which offered improved reliability and a simpler activation mechanism. The M60 was subsequently supplemented by the M81 Fuse Igniter, which can initiate both time blasting fuse and shock tube. The M81 remains the current standard fuse igniter in US military demolition kits.

This lesson is intended for educational and training purposes. All ordnance should be considered dangerous until proven safe by qualified personnel. Never handle suspected explosive devices—report findings to military or law enforcement authorities.