The M829 is an American armor-piercing fin-stabilized discarding sabot ( APFSDS)

kinetic energy penetrator A kinetic energy penetrator (KEP), also known as long-rod penetrator (LRP), is a type of ammunition designed to penetrate vehicle armour using a flechette-like, high- sectional density projectile. Like a bullet or kinetic energy weapon, this ty ...

tank A tank is an armoured fighting vehicle intended as a primary offensive weapon in front-line ground combat. Tank designs are a balance of heavy firepower, strong armour, and battlefield mobility provided by tracks and a powerful engine; ...

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. Modeling was done at the

Ballistic Research Laboratory The Ballistic Research Laboratory (BRL) was a research facility under the U.S. Army Ordnance Corps and later the U.S. Army Materiel Command that specialized in ballistics as well as vulnerability and lethality analysis. Situated at Aberdeen Pr ...

Aberdeen Proving Ground Aberdeen Proving Ground (APG) is a U.S. Army facility located adjacent to Aberdeen, Harford County, Maryland, United States. More than 7,500 civilians and 5,000 military personnel work at APG. There are 11 major commands among the tenant units, ...

, which was incorporated into the

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in 1992. The round is specifically designed for the 120 mm M256 main gun on the Abrams M1A1 and M1A2

main battle tanks A main battle tank (MBT), also known as a battle tank or universal tank or simply tank,Ogorkiewicz 2018 p222 is a tank that fills the role of armour-protected direct fire and maneuver in many modern armies. Cold War-era development of more po ...

. The penetrator is carried by a sabot during its acceleration in the gun barrel.

Variants

M829

The M829 dart has a ballistic nose and six tail fins made of

aluminum Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

. It is carried in the gun tube by a four-piece aluminum sabot, which separates into four "petals" soon after the round leaves the gun tube. The propulsion system uses an obturating case base with a semi-combustible cartridge wall. It has a total weight of and a DU penetrator with a rod diameter, which reaches a

muzzle velocity Muzzle velocity is the speed of a projectile (bullet, pellet, slug, ball/ shots or shell) with respect to the muzzle at the moment it leaves the end of a gun's barrel (i.e. the muzzle). Firearm muzzle velocities range from approximately t ...

of using of JA-2 propellant. Its maximum effective range is . According to

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, the M829 is capable of penetrating of RHA steel armor at up to a range. The original M829 is no longer in production and has been succeeded by the M829A1, M829A2, and M829A3. The corresponding training round is the M865, costing $1,121.

M829A1

The M829A1 (nicknamed the "

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" by

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tank crews) proved itself in 1991 against

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i T-55 and

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M tanks during Operation Desert Storm. The M829A1 round weighs and has an overall length of . The of JA-19 propellant creates a chamber pressure of , which results in a muzzle velocity of . The penetrator and its sabot together weigh . The mass of the penetrator alone is . The effective target range is .

M829A2

The next generation ammunition, called 120 mm APFSDS-T M829A2, entered service in 1994 and is the armor-piercing ammunition currently being produced by General Dynamics Ordnance and Tactical Systems for the 120 mm M256 gun of M1A1 and M1A2 tanks. It is a technology improvement over the M829A1. The new ammunition's performance gains, while classified, result from several new features. These include a special manufacturing process that improves the structural quality of the depleted uranium penetrator. This, the use of new composites for the sabot, and a new propellant provide superior penetrator performance. Combined, these features increase the muzzle velocity of the M829A2 to approximately 100 m/s greater than the M829A1's (up to approximately 1,675 m/s) while operating at slightly lower pressure. The projectile's length is 780 mm, its mass 9 kg. On 6 May 2014, the U.S. Army announced that it awarded a US$12 million contract to defense contractor General Dynamics for the demilitarization and disposal of 78,000 aging depleted-uranium (DU) tank rounds as newer rounds are added to the U.S. war reserves. The contract includes M829A1 and M829A2 rounds. M829A3 Cross Section

M829A3

With the Soviet creation of the Kontakt-5 Explosive Reactive Armor ( ERA), the M829A3 was the US immediate response, developed in part to take on this new ERA type. It completed type classification standard in March 2003. Very little is publicly known about the round, perhaps due to export restrictions (see International Traffic in Arms Regulations (ITAR)). The M829A3 uses a more efficient

propellant A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or another motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicle ...

, RPD-380, boosting its muzzle velocity. The M829A3 round has a total mass of and length of . It uses of RPD-380 stick propellant, accelerating the sabot and depleted-uranium rod penetrator assembly, and a muzzle velocity of . From patents submitted by Orbital ATK, the penetrator is composed of two sections, an approximately steel tip and the rest composed of a 630-millimeter (24.8 in) depleted uranium rod with aluminum fins and a tracer base. The penetrator diameter was also increased from to , improving penetrator strength by 67% significantly increasing its resistance to ERA bursting plates as used in Russian ERA. The steel tip is used to defeat the ERA by detonating it early, causing the resulting ERA bursting plate to only partially affect the main DU rod which is used to complete the penetration through armor. The resulting muzzle energy is The penetration as per the Lanz Odermatt calculator is about a total penetration of 680-millimeters (26.7717 in) up to possibly 720-millimetres of RHA to account for any discrepancies in measurement. The M829A3 is only used for training with a switched plastic sabot round. This is calculated from the 100-millimeter (3.9 in) steel tip adjoined to a 630-millimeter (24.8 in) DU body that is 25-millimeter (0.98 in) thick at 1550m/s (5085 fps) with a target RHA BHN of 250. The sabot is of composite material. This variant is unofficially referred to by Abrams tank crews as the "super sabot". Although the M829A3 fired from the 44-caliber M256 gun has a lower muzzle velocity than 120 mm shells fired from the Rheinmetall 55-caliber gun barrel or Russian

2A46 125 mm gun The 2A46 (also called D-81TM) is a 125 mm/L48 smoothbore cannon of Soviet origin used in several main battle tanks. It was designed by OKB-9 (Artillery Plant No. 9) in Yekaterinburg. Description It was developed by the Spetstekhnika Design ...

ammunition, it uses a larger penetrator with increased mass to increase imparted kinetic energy.

M829A4

The A4 (formerly E4) variant was under development by General Dynamics Ordnance & Tactical Systems and

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(ATK) until ATK received a $77 million, three-year contract on 11 July 2011 to develop and qualify the M829A4 Advanced Kinetic Energy (AKE) round for the U.S. Army's M1A2 SEP (System Enhancement Package) Abrams MBT. The M829A4 is a fifth-generation APFSDS-T cartridge using a depleted-uranium penetrator with a three-petal composite sabot; the penetrator includes a low-drag fin with a tracer and a windshield and tip assembly.Fifth generation Army tank cartridge reports loudly for duty
- Army.mil, 18 April 2014 Its propellant maintains consistent muzzle velocities across operational temperatures from . The new Advanced Combustible Cartridge Case is similar to previous models but has a relocated skive joint placement for better crew-member safety during handling. The initial order for 2,501 M829A4 rounds in 2014 had a unit cost of $10,100 each. On 20 July 2015, Orbital ATK announced that the M829A4 had passed First Article Acceptance Testing and was entering production. On 12 October 2015, Orbital ATK announced the round had recently received type classification as the M829A4 and was awarded a full-rate production contract to begin in early 2016.

References

External links

M829A1 Technical details and images, from Global Security

PEO Ammunition Systems
{{Webarchive, url=https://web.archive.org/web/20181106171753/https://www.dau.mil/cop/ammo/DAU%20Sponsored%20Documents/PEO%20Ammo%20Portfolio%20Book%202017.pdf , date=6 November 2018
M829A4 (formerly M829E4) Armor Piercing, Fin Stabilized, Discarding Sabot – Tracer (APFSDS-T)
Anti-tank rounds Military equipment introduced in the 1990s Tank ammunition