Soviet OF-412 100mm HE Projectile
1. Overview
The OF-412 (Russian: ОФ-412) is a Soviet-designed 100mm high-explosive fragmentation (HE-Frag) artillery projectile, and one of the most widely produced and distributed 100mm projectiles in military history. Originally developed during World War II for use with the D-10 series of 100mm guns and the BS-3 field gun, the OF-412 became the standard HE round for the T-54/T-55 family of tanks — the most produced tank series in history. As a result, the OF-412 and its variants have been manufactured across dozens of countries and encountered in virtually every major conflict from the late 1940s through the present day.
2. Country/Bloc of Origin
- Country: Soviet Union (USSR)
- Time Period: Developed during World War II (circa 1944), entering service alongside the D-10 gun on the SU-100 tank destroyer
- Bloc Affiliation: Warsaw Pact / Soviet-aligned states
- International Production: Produced under license or copied by numerous countries including China (as part of the Type 59 tank program), Czechoslovakia, Bulgaria, Romania, Yugoslavia (as the M63/M63P1), Egypt, North Korea, and others
- Distribution: Encountered worldwide wherever T-54/T-55 tanks or BS-3 guns have been exported or captured
3. Ordnance Class
- Type: Artillery projectile (gun-fired)
- Role: High-explosive fragmentation (HE-Frag) — general-purpose engagement of personnel, light vehicles, field fortifications, and soft targets
- Delivery Method: Gun-fired from 100mm rifled weapons systems; spin-stabilized; nose-fuzed
4. Ordnance Family / Nomenclature
- Official Designation: OF-412 (ОФ-412) — the projectile designation
- Complete Round Designation: UOF-412 (УОФ-412) — designates the complete cartridge including projectile, cartridge case, propellant, and primer
- GRAU Index: Part of the 412 ammunition family for the D-10 gun
- Related Family Members:
- BR-412: Armor-piercing high-explosive (APHE) projectile
- BR-412B / BR-412D: Ballistic-capped APHE variants
- D-412: Smoke projectile
- 3BK5M: HEAT projectile (later addition)
- Foreign Copies:
- M63 / M63P1: Yugoslavian production copies
- Type 59 ammunition: Chinese production copies
- Compatible Weapons: D-10T, D-10S, D-10T2S, BS-3 (M1944), and compatible 100mm rifled guns
5. Hazards
- Primary Hazards: Blast and fragmentation; the steel projectile body produces high-velocity lethal steel fragments
- Explosive Content: TNT, approximately 1.46 kg (3.22 lbs)
- Sensitivity: The nose-mounted PD fuze is the primary sensitivity concern; in UXO condition, the fuze may be armed and sensitive to mechanical disturbance
- UXO Considerations: Extremely common UXO item worldwide; encountered in conflict zones from Southeast Asia to the Middle East, Africa, and the former Soviet Union. The sheer production volume of T-55 tanks (over 100,000 produced) and BS-3 guns means OF-412 rounds have been fired in enormous quantities
- Environmental Degradation: Steel body corrodes over time; fuze mechanisms may deteriorate unpredictably. TNT is relatively stable but can exude or crystallize under temperature cycling, potentially increasing sensitivity
- Special Hazards: As a fixed round (projectile crimped to cartridge case), complete unfired rounds present additional propellant hazards; separated projectiles found as UXO present primarily fuze and explosive hazards
6. Key Identification Features
- Caliber: 100mm (3.94 inches)
- Projectile Weight: 15.6 kg (34.4 lbs)
- Shape: Conventional artillery projectile with streamlined ogive, cylindrical body, and boattail base
- Rotating Band: Single copper or gilding metal rotating band near the base
- Body Material: Steel
- Color and Markings: Painted dark grey with black stenciled markings in Cyrillic indicating designation (ОФ-412), lot number, year of manufacture, and factory code
- Fuze Well: Threaded nose cavity for point-detonating fuze
- Complete Round: As a fixed cartridge, the complete UOF-412 round has an overall weight of approximately 30.2 kg with the propellant charge weighing approximately 5.5 kg
7. Fuzing Mechanisms
- Fuze Type: Nose-mounted, point-detonating (PD), mechanical fuze
- Standard Fuze: V-429 or V-429E
- Function Settings: Selectable between super-quick (SQ) and delayed action; SQ detonates on surface impact for maximum fragmentation effect against personnel; delay allows penetration into field fortifications or earthworks before detonation
- Arming Mechanism: Mechanical arming through setback (acceleration) and centrifugal (spin) forces generated during firing
- Safety Features: Bore-safe design with mechanical interrupters; fuze does not arm until projectile has traveled a safe distance from the muzzle
- Primer Types: KV-U, KV-13, or KV-13U percussion primers in the cartridge case base
8. History of Development and Use
The OF-412 was developed during World War II as part of the ammunition family for the D-10 100mm gun, itself derived from a naval gun design by F.F. Petrov’s design bureau. The D-10 first entered service on the SU-100 tank destroyer in late 1944, providing Soviet forces with a powerful weapon capable of defeating German heavy armor including the Panther and Tiger I tanks at combat ranges.
After the war, the D-10 was selected as the main armament for the T-54 tank (entering production in 1947) and subsequently the T-55 (from 1958). These became the most-produced tank series in history, with over 100,000 T-54/T-55 variants manufactured. Every one of these tanks required stocks of 100mm ammunition, making the OF-412 one of the most mass-produced artillery projectiles ever made.
The OF-412 was simultaneously employed with the BS-3 (M1944) towed 100mm field gun, which served as both an anti-tank weapon and field artillery piece. The BS-3 saw widespread service across the Soviet Union and its allies from World War II through the Cold War.
The OF-412 has seen combat in virtually every major conflict involving Soviet-equipped forces since 1945, including the Korean War, the Arab-Israeli Wars, the Vietnam War, numerous African conflicts, the Iran-Iraq War, both Gulf Wars, the Yugoslav Wars, and most recently the ongoing conflict in Ukraine where T-55 tanks have been reactivated from storage.
The projectile continues to be manufactured in several countries and remains in active service worldwide. It is one of the most commonly encountered UXO items in post-conflict clearance operations globally.
9. Technical Specifications
| Parameter | Specification |
|---|---|
| Caliber | 100mm |
| Projectile Type | HE-Frag (High-Explosive Fragmentation) |
| Projectile Weight | 15.6 kg (34.4 lbs) |
| Complete Round Weight | 30.2 kg (66.6 lbs) |
| Explosive Fill Type | TNT |
| Explosive Fill Weight | 1.46 kg (3.22 lbs) |
| Body Material | Steel |
| Fuze | V-429 / V-429E (PD, SQ/Delay) |
| Muzzle Velocity | ~900 m/s (2,953 ft/s) |
| Maximum Range | ~16,000 m (from BS-3) |
| Propellant Charge Weight | 5.5 kg |
| Loading Type | Fixed (single-piece cartridge) |
| Operating Temperature | -40°C to +60°C |
| Shelf Life | 10 years (standard storage conditions) |
| Packing | 2 rounds per wooden box; box dimensions 1,206 x 444 x 264mm; gross weight 84 kg |
10. Frequently Asked Questions
Q: Why is the OF-412 so commonly encountered as UXO worldwide? A: The OF-412 is the standard HE round for the T-54/T-55 tank series — the most produced tank in history with over 100,000 built and exported to dozens of countries across every continent. This means OF-412 rounds have been fired in enormous quantities in conflicts spanning from Korea and Vietnam through the Middle East, Africa, and Europe. Any conflict involving Soviet-equipped forces likely involved extensive use of this projectile.
Q: What is the difference between the OF-412 designation and the UOF-412? A: “OF-412” refers specifically to the projectile itself (the HE-Frag component). “UOF-412” designates the complete fixed cartridge, which includes the projectile, the brass or steel cartridge case, the propellant charge, and the percussion primer. In Soviet nomenclature, the “U” prefix generally denotes the complete round.
Q: How does the OF-412 compare to NATO 100mm ammunition? A: NATO does not widely use 100mm as a standard caliber for tank or field guns, making the OF-412 largely unique to Soviet-pattern forces. The closest NATO equivalents in terms of role would be 105mm HE projectiles (such as the M1) for howitzer support or 105mm tank gun rounds. The OF-412’s relatively small explosive fill (1.46 kg TNT) compared to its total weight reflects the dual anti-armor/anti-personnel design philosophy of the D-10 gun system.
Q: What are the primary weapons that fire the OF-412? A: The D-10 gun family is the primary weapon system: the D-10T and D-10T2S variants arm the T-54 and T-55 tanks respectively, the D-10S arms the SU-100 tank destroyer, and the BS-3 (M1944) is the towed field gun variant. Chinese copies (Type 59 tank gun) and Romanian copies (A407) also fire compatible ammunition.
Q: Can the OF-412 be encountered in its complete fixed-round configuration as UXO? A: Yes. While most UXO encounters involve separated projectiles that were fired and failed to detonate, complete unfired UOF-412 rounds can also be found in abandoned ammunition stores, destroyed vehicles, or discarded stockpiles. Complete rounds present additional hazards from the propellant charge and percussion primer in addition to the explosive projectile fill.
Q: What fuze malfunctions can lead to the OF-412 becoming UXO? A: Common causes include impact at insufficient angle or velocity for the fuze to function (e.g., ricochet or grazing impact), fuze manufacturing defects, insufficient spin due to worn gun rifling, environmental contamination of fuze mechanisms, or impact with very soft ground that absorbs energy before the fuze can function. In all cases, the projectile should be treated as if the fuze is armed and sensitive.
Q: Is the OF-412 still in production today? A: Yes. The OF-412 continues to be manufactured by several countries including Bulgaria, Romania, and others that maintain T-55 fleets or export compatible ammunition. The ongoing conflict in Ukraine has increased demand for 100mm ammunition as older T-55 tanks have been reactivated from storage by multiple parties.
⚠️ 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.