Chinese Type 55 120mm HE Mortar
1. Overview
The Type 55 120mm HE Mortar is a Chinese-manufactured high-explosive fragmentation mortar projectile produced by NORINCO (China North Industries Corporation) for use with 120mm smoothbore mortar systems. The Type 55 mortar is a Chinese production variant of the Soviet OF-843 family of 120mm mortar ammunition, designed for use with the Chinese Type 55 mortar (itself a heavier, more robust version of the Soviet 120-PM-43 mortar). This ammunition has been widely exported and is encountered in conflict zones across Asia, Africa, and the Middle East. The thick cast iron body and substantial fragmentation capability make it an effective anti-personnel and anti-materiel weapon, while its prevalence in export markets makes it a common UXO item for clearance operations worldwide.
2. Country/Bloc of Origin
- Country: People’s Republic of China
- Manufacturer: NORINCO (China North Industries Corporation)
- Time Period: Developed in the 1950s as part of China’s program to domestically produce Soviet-pattern military equipment; the Type 55 mortar system was introduced alongside Chinese-manufactured ammunition
- Lineage: Based on the Soviet OF-843/OF-843B 120mm mortar design, which was itself the standard HE round for the Soviet 120-PM-43 mortar introduced in 1943
- Export: Widely exported to Chinese client states and arms customers across Africa, Asia, and the Middle East; also supplied through military assistance programs
3. Ordnance Class
- Type: Mortar (mortar-fired)
- Role: High-explosive fragmentation (HE-Frag) — engagement of personnel, field fortifications, light vehicles, and area targets through indirect fire
- Delivery Method: Muzzle-loaded, drop-fired from 120mm smoothbore mortar systems; fin-stabilized
4. Ordnance Family / Nomenclature
- Official Designation: Type 55 120mm HE Mortar (Chinese designation)
- Soviet Parent Design: OF-843 / OF-843B
- Related Chinese Designations:
- Type 53: Earlier Chinese copy of the Soviet 120-PM-43 mortar and its ammunition; the Type 55 is a heavier, more robust development
- Type 843 / Type 843B: Chinese-manufactured copies of the Soviet OF-843/OF-843B mortar designations
- Compatible Mortar Systems:
- Chinese Type 55 mortar (primary system)
- Chinese Type 53 mortar
- Chinese W86 mortar (can fire older pattern 120mm ammunition including Type 55)
- Soviet 120-PM-43 (Mod. 1943)
- Soviet 120-PM-38 (Mod. 1938)
- Soviet 2B11 Sani
- Any compatible 120mm smoothbore mortar
- Compatible Fuzes: Chinese Type 2 BD (base-detonating) fuze, M-12 PD fuze, and equivalent Soviet-pattern mortar fuzes
5. Hazards
- Primary Hazards: Blast and fragmentation; the very thick cast iron body produces numerous lethal fragments
- Explosive Fill: TNT or TNT-based mixture (such as TD-50, a Soviet-pattern 50/50 mixture of TNT and dinitronaphthalene, or Amatol); approximately 1.4–1.6 kg depending on variant and manufacturer
- Cast Iron Body: The Type 55 mortar, like its Soviet OF-843 parent, has an extremely thick cast iron body. This is significant for EOD considerations:
- Thick-cased munitions are more challenging to defeat with thermal disposal techniques (e.g., thermite lance attack)
- The thick iron body produces a large number of effective fragments (approximately 2,900+ fragments in similar OF-843B designs)
- Fuze Sensitivity: The nose-mounted point-detonating fuze (M-12 type or equivalent) is impact-activated and may be armed in UXO condition; super-quick and delay settings affect sensitivity
- UXO Considerations: Commonly encountered across conflict zones where Chinese arms exports have reached; 120mm mortar rounds have significant dud rates in soft ground conditions where impact energy is absorbed before fuze function
- Propellant Charges: The Type 55 mortar uses augmenting propellant charges (increments) attached to the tail boom; these additional propellant charges are flammable and present fire hazards
- Shelf Life: When properly stored, the ammunition has a shelf life of approximately 10 years, but export stocks are frequently encountered well beyond this period in degraded storage conditions
6. Key Identification Features
- Caliber: 120mm (4.72 inches)
- Overall Length: Approximately 674mm (26.5 inches) including fuze and tail assembly
- Weight: Approximately 15.9–16 kg (35 lbs)
- Body Shape: Teardrop/streamlined shape with a pointed nose (fuze adapter), cylindrical main body, and tapered tail section
- Body Material: Thick cast iron (spheroidal graphite cast iron in some variants)
- Gas Check Bands: Multiple gas check bands (grooves) along the major diameter of the body — typically 5 bands; these are distinctive identification features of the 120mm mortar family
- Tail Assembly: Stabilizing tail boom with flash holes and multiple fins (typically 10 fins with 18 flash holes in the OF-843B pattern); the tail boom is assembled to the base of the mortar body
- Fuze Well: Nose-mounted fuze well with adapter for PD fuze
- Color and Markings: Typically painted light or dark grey; Chinese markings include designation and lot information, often in Chinese characters; some export variants may have markings in other languages
- Propellant Increments: Augmenting charges may be visible attached to or packaged with the tail assembly
7. Fuzing Mechanisms
- Primary Fuze: Point-detonating (PD) fuze, M-12 type or Chinese equivalent (such as Type 2 BD fuze)
- Function Settings: Typically selectable between super-quick (SQ) and delay
- Super-Quick: For engagement of personnel and soft targets in the open; detonates on surface contact for maximum fragmentation dispersal
- Delay: For engagement of field fortifications and bunkers; the fuze delays detonation to allow penetration into earthworks before functioning
- Arming: The fuze arms during the mortar firing sequence through setback forces (acceleration upon firing) and may incorporate a centrifugal safety element despite being a smoothbore (fin-induced rotation)
- Detonator and Booster: The fuze assembly contains a detonator and booster charge that initiates the main explosive fill
- Spacers: Cardboard spacers may be placed at the bottom of the fuze well underneath the detonator to take up empty space
- Safety Features: Basic bore-safety mechanisms; however, the simplicity of mortar fuze designs means that safety features are less sophisticated than those found on artillery fuzes — increasing the UXO hazard
8. History of Development and Use
China’s production of 120mm mortar ammunition traces directly to the Soviet Union’s assistance in the 1950s, when the People’s Republic of China received technology transfers and manufacturing rights for a wide range of Soviet military equipment under the Sino-Soviet cooperation agreements.
The Soviet 120-PM-43 mortar was one of the most successful mortar designs of World War II, providing Soviet infantry battalions with heavy indirect fire support. China initially produced a direct copy as the Type 53 mortar with corresponding ammunition. NORINCO subsequently developed the Type 55 as a more robust and heavier variant that offered improved durability and reliability, though at the cost of increased weight.
The Type 55 mortar and its ammunition were adopted by the People’s Liberation Army (PLA) and became a standard heavy mortar system. The mortar was eventually replaced in PLA service by the W86 120mm mortar (a lighter, more modern design with increased range), though older Type 55 systems and their ammunition remained in reserve stocks and continued to be exported extensively.
Chinese 120mm mortar ammunition, including the Type 55 HE, has been exported to numerous countries across Africa, Asia, and the Middle East. It has seen combat use in multiple conflicts including the Vietnam War (used by North Vietnamese and Viet Cong forces), various African civil wars, the Iran-Iraq War, and conflicts in the Middle East. Chinese-manufactured 120mm mortar rounds have been documented by Conflict Armament Research and other organizations in conflict zones including Syria, Iraq, Libya, Yemen, and multiple sub-Saharan African countries.
The Type 55 HE mortar is compatible with virtually any 120mm smoothbore mortar system, including Soviet-designed mortars, copies produced by other countries, and even some Western 120mm systems. This cross-compatibility has facilitated its widespread distribution and use.
As a UXO item, the Type 55 120mm mortar presents the same challenges as other thick-cased 120mm mortars. The extremely thick cast iron body makes disposal using thermal lance techniques more difficult and time-consuming than with thin-cased munitions, requiring EOD technicians to select appropriate disposal methods.
9. Technical Specifications
| Parameter | Specification |
|---|---|
| Caliber | 120mm |
| Type | HE-Frag Mortar |
| Manufacturer | NORINCO (China) |
| Parent Design | Soviet OF-843 / OF-843B |
| Overall Length | ~674mm (26.5 in) |
| Weight | ~15.9–16 kg (35 lbs) |
| Body Material | Cast iron |
| Explosive Fill Type | TNT or TD-50 (TNT/dinitronaphthalene) or equivalent |
| Explosive Fill Weight | ~1.4–1.6 kg |
| Gas Check Bands | 5 |
| Tail Fins | ~10 fins |
| Flash Holes | ~18 |
| Fuze | PD (M-12 type / Chinese Type 2 BD) |
| Maximum Range | ~5,700–5,850 m (Type 55 mortar) |
| Muzzle Velocity | ~272 m/s (892 ft/s) |
| Rate of Fire | Up to 15 rounds/minute (mortar system) |
| Compatible Systems | Type 55, Type 53, W86, 120-PM-38, 120-PM-43, 2B11, and equivalent 120mm smoothbore mortars |
| Effective Fragments | ~2,900+ (based on OF-843B pattern data) |
| Operating Temperature | -40°C to +60°C |
10. Frequently Asked Questions
Q: What is the relationship between the Type 55 mortar and the Soviet OF-843? A: The Type 55 120mm HE mortar is a Chinese production variant of the Soviet OF-843 family. The designs are functionally equivalent and share the same basic dimensions, weight, explosive fill specifications, and compatibility with standard 120mm smoothbore mortar systems. The primary differences are in manufacturing origin (Chinese vs. Soviet factories), marking conventions (Chinese characters vs. Cyrillic), and potential minor variations in explosive fill composition and body metallurgy.
Q: Why is the thick cast iron body significant for EOD operations? A: The extremely thick cast iron body of the Type 55 (and OF-843 family) mortars presents a specific challenge for disposal operations. Thermal attack methods such as thermite lance require significantly more time and material to penetrate thick-cased munitions compared to thin-walled ordnance. EOD technicians must positively identify the target munition and select disposal techniques appropriate for thick-cased items. This may favor alternative disposal methods such as explosive demolition over thermal attack.
Q: How can the Type 55 mortar be distinguished from Soviet OF-843 variants? A: In the field, the primary distinguishing factor is the marking system. Chinese-manufactured rounds will typically bear markings in Chinese characters, while Soviet and Eastern European variants use Cyrillic script. The physical dimensions and overall appearance are essentially identical. Some metallurgical differences in the cast iron composition may exist but are not field-identifiable. If markings are illegible, positive identification of manufacturing origin may not be possible without technical analysis.
Q: Where is the Type 55 mortar most commonly encountered? A: The Type 55 is most commonly encountered in countries that received Chinese military equipment and arms exports, particularly in Southeast Asia (Vietnam, Cambodia, Laos), Sub-Saharan Africa, and the Middle East. It is also encountered in conflict zones where Chinese-manufactured ammunition has been diverted or captured, including Syria, Iraq, and Libya. Chinese 120mm mortar rounds are among the most widely exported ammunition types in the world.
Q: Can the Type 55 mortar be fired from non-Chinese mortar systems? A: Yes. The Type 55 is compatible with any standard 120mm smoothbore mortar system, including Soviet-designed systems (120-PM-38, 120-PM-43, 2B11 Sani), copies produced by other countries (Bulgarian, Romanian, etc.), and the Chinese W86 mortar. This cross-compatibility is a deliberate feature — the original Soviet 120mm mortar was designed to be universal across the family of 120mm smoothbore mortars, and all subsequent copies maintain this compatibility.
Q: What is TD-50 explosive filler? A: TD-50 is a Soviet-standard explosive mixture consisting of 50% TNT (trotyl) and 50% DNN (dinitronaphthalene). It is a relatively low-cost explosive fill used in mortars and other munitions where the priority is adequate blast effect at minimal cost. TD-50 is less powerful than pure TNT but is easier and cheaper to produce. Some variants may use Amatol (TNT and ammonium nitrate mixture) as an alternative fill. The exact fill composition may vary by production batch and era.
Q: How does the 120mm mortar’s fragmentation pattern affect target engagement? A: The thick cast iron body of the Type 55 fragments into approximately 2,900 or more effective fragments upon detonation. The heavy fragments maintain lethality across a significant radius. The combination of blast and fragmentation makes the 120mm mortar effective against personnel in the open, in light field fortifications, and in buildings. The delay fuze setting allows penetration into earthen fortifications before detonation, maximizing the effect against dug-in positions.
⚠️ SAFETY WARNING: All ordnance should be considered dangerous until proven safe by qualified EOD or demining personnel. Never approach, handle, or attempt to move suspected UXO. Report all findings to appropriate military or civilian authorities immediately. This material is for educational and identification training purposes only.