Mk-77 firebomb

Also known as

Mk-77
Mark 77
Mk 77 fire bomb
Mk 77 firebomb
MK-77 firebomb

The Mk-77 firebomb is a U.S. air-dropped incendiary bomb family used as the primary firebomb in Marine Corps training references. Later Mod 4 references describe a roughly 500-pound weapon filled with about 75 gallons of fuel/gel mixture, and Navy AV-8B loadout tables list Mk-77 (Mod 2/4) among the Harrier's air-to-ground stores.

Mk-77 firebomb, Incendiary bomb, Munitions

Image source: USMC MK-77 fire bomb explodes

Profile / Specs

Profile

Origin: United States
Built by: U.S. military ordnance contractors
Type: Incendiary bomb

bomb incendiary air-dropped

Specifications

Weight: About 520 lb
Fuel/gel mixture: 75 gallons
Guidance: Unguided free-fall
Release altitude: Very low altitude
Trajectory: Erratic in flight

Variants

Mk 77 Mod 2
Mk 77 Mod 4
Mk 77 Mod 5

Carrier Aircraft

Navy AV-8B loadout references list Mk-77 (Mod 2/4) fire bombs among the Harrier's air-to-ground stores.

Carrier

Carrier type

Carriage evidence

AV-8B Harrier II, Vertical/short takeoff and landing attack aircraft, Aircraft & UAVs

AV-8B Harrier II

V/STOL attack aircraft

The Navy fact file lists Mk-77 (Mod 2/4) fire bombs among the AV-8B's air-to-ground stores.

Sources: NHHC AV-8B PDF Fact File

Service And Conflict Use

Service History

In service: Referenced in U.S. Marine Corps fire-support training and AV-8B Harrier II loadout references.
Used by: United States Marine Corps

Related Weapon Systems

1,000-pound drop bomb, Free-fall bomb, Munitions

Munitions1,000-pound drop bombFree-fall bombThe 1,000-pound drop bomb is a U.S. low-drag free-fall general-purpose bomb class represented by the Mk 83 and BLU-110 body family. U.S. Army ordnance references describe the BLU-110 as the Mk 83 family bomb body used in standard air-launched munitions, and Air Force documentation places the 1,000-pound BLU-110/MK 83 warhead family in JDAM payload use.

220 lb bomb, 100 kg general-purpose bomb, Munitions

Munitions220 lb bomb100 kg general-purpose bombThe 220 lb bomb is a Soviet 100 kg-class freefall aviation bomb associated with the FAB-100 family. Deagel describes the modern FAB-100 as a low-drag, single-nose-fuze bomb introduced in 1962, and DCS L-39ZA reference material lists FAB-100 among the aircraft's carried bombs.

250 kg bomb, Unguided air-dropped bomb, Munitions

Munitions250 kg bombUnguided air-dropped bombThe 250 kg bomb is a generic 250 kilogram air-dropped bomb class documented in F-7NI armament references. DefenseNigeria describes the F-7Ni as carrying bombs on four wing pylons, while AviationsMilitaires.net explicitly lists 250 kg bombs in the F-7NI armament fit.

500 kg bomb, Unguided air-dropped bomb, Munitions

Munitions500 kg bombUnguided air-dropped bombThe 500 kg bomb is a heavy unguided air-dropped bomb class. DefenseNigeria describes the F-7NI as carrying unguided bombs weighing between 250 kg and 500 kg, and Munitions India markets a 500 KG GP Bomb in the same weight class.

FAB-100M-62 GPB, 100 kg general-purpose bomb, Munitions

MunitionsFAB-100M-62 GPB100 kg general-purpose bombThe FAB-100M-62 GPB is a Soviet-origin 100 kg free-fall general-purpose bomb in the FAB M62 family. WeaponsSystems.net lists the M62 series as a Soviet aviation-bomb family introduced in the early 1960s, and CMO-DB shows this exact variant in a Harbin H-5 Beagle loadout.

FAB-1500M-54 GPB, 1,500 kg general-purpose bomb, Munitions

MunitionsFAB-1500M-54 GPB1,500 kg general-purpose bombThe FAB-1500M-54 GPB is a Soviet-origin 1,500 kg general-purpose bomb produced by JSC NPO Basalt in Russia. Reference data lists it as a 1,550 kg weapon with a 2.84 m length, 0.64 m diameter, and 675.6 kg explosive fill, and CMO-DB includes it in Harbin H-5 Beagle loadouts.

Sources

NHHC AV-8B PDF Fact FilePublisher: Naval History and Heritage Command | Note: Supports the AV-8B Harrier II air-to-ground stores list that includes Mk-77 (Mod 2/4) fire bombs. | Accessed: 2026-06-27 Principles of Fire SupportPublisher: U.S. Marine Corps Training Command | Note: Supports the Mk-77 Firebomb as the primary firebomb and the 75-gallon fuel/gel load with a 520 lb weight figure. | Accessed: 2026-06-27 USMC MK-77 fire bomb explodesPublisher: U.S. Marine Corps | Note: Supports image provenance for the public-domain Mk-77 fire bomb photograph. | Accessed: 2026-06-27