M829

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The M829 is an American Armor-Piercing, Fin-Stabilized, Discarding Sabot (APFSDS) tank round designed specifically for the 120mm M256 main gun on the Abrams M1A1 and M1A2 main battle tanks. This sub-caliber anti-tank round is essentially a dart made of a depleted uranium (DU) alloy which gives it good penetration against nearly all known types of tank armor. The penetrator is carried by a sabot during its acceleration in the gun barrel.

History[edit]

Perhaps see Armour-piercing fin-stabilized discarding sabot, and sabot for applicable historical references.

Design[edit]

Perhaps see Armour-piercing fin-stabilized discarding sabot, and sabot for applicable design references.

Variants[edit]

M829[edit]

The M829 has a ballistic nose and five tail fins made of aluminum. 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 41.1 lb (18.6 kg) and utilizes a 627 mm (24.7 in) DU penetrator with a 27 mm rod diameter,[1] which will reach a muzzle velocity of 1,670 metres per second (5,500 ft/s) using of 8.1 kg (18 lb) of JA-2 propellant. Maximum effective range is 3,000 m (3,300 yd). According to Jane's, the M829 is capable of penetrating 540 mm (21 in) of RHA steel armor at up to a 2,000 m (2,200 yd) range.[2] 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.[1]

M829A1[edit]

The M829A1 (nicknamed the "Silver Bullet" by Operation Desert Storm tank crews) proved itself in 1991 against Iraqi T-55 and T-72 tanks during Operation Desert Storm. However, its effectiveness has been reduced by modern explosive reactive armor (ERA) such as the Russian Kontakt-5, which led to the rapid development of the M829A3 round (which in turn led to the development of the newest Russian Relikt ERA). The M829A1 round weighs 20.9 kg (46 lb) and has an overall length of 984 mm (38.7 in). The 7.9 kg (17 lb) of JA-19 propellant creates a chamber pressure of 5,600 bars (~81,220 psi), which results in a muzzle velocity of 1,575 m/s (5,170 ft/s). The 684 mm (26.9 in)-long penetrator together with its sabot weighs 9 kg (20 lb). The mass of the penetrator alone is 4.6 kg (10 lb). The effective target range is 3,000 m (3,300 yd).[3] Point-blank the M829A1 is estimated to penetrate 670 mm (26 in) of steel armor, which decreases to 620 mm (24 in) at 1,000 m (1,100 yd), and to 570 mm (22 in) at 2,000 m (2,200 yd). At 4,000 m (4,400 yd), it is believed to still be able to penetrate 460 mm (18 in) of steel armor.[4]

M829A2[edit]

M829A2 cross-section

The M829A2 APFSDS is a third-generation anti-tank round based on the M829A1 penetrator and designed for the 120-mm M256 main gun in the M1A1 (or later) Abrams main battle tank. The M829A2 featured several improvements over the M829A1, including giving it increased penetration over previous types of anti-tank rounds; better manufacturing processes for the penetrator; and a special manufacturing process that partially cut the propellant charge to allow it to behave ballistically like a granular propellant bed, while loading like a stick charge.[1] The M829A2 was also the first APFSDS round to use a carbon fiber-reinforced composite sabot, reducing the weight of the overall round and allowing for the larger penetrator. Combined, these features boosted the muzzle velocity of the M829A2 to approximately 100 m/s greater than the M829A1 to 1,680 m/s (5,500 ft/s), while operating at a slightly lower gun-chamber pressure. The M829A2 entered service in the United States Army in 1993.

On 6 May 2014, the US 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.[5]

M829A3[edit]

The M829A3 design was driven by the need to counter KE-effective explosive reactive armor (ERA).[6] 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).[7] The M829A3 uses a more efficient propellant, RPD-380, boosting its muzzle velocity. The M829A3 round has a total mass of 22.3 kg (49 lb) and length of 892 mm (35.1 in). It uses 8.1 kg (18 lb) of RPD-380 stick propellant, accelerating a 10 kg (22 lb) depleted uranium rod penetrator, which can be estimated from cutaway mock-ups to be 800 mm (31 in) long, to a muzzle velocity of 1,555 m/s (5,100 ft/s). The sabot is of composite material. This variant is unofficially referred to by Abrams tank crews as the "super sabot".[8] It costs around $8,500.[1] 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 ammunition, it uses a larger penetrator with increased mass to increase imparted kinetic energy.[9]

M829A4[edit]

The A4 (formerly E4) variant was under development by General Dynamics Ordnance & Tactical Systems and Alliant Techsystems (ATK)[10] 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 US Army's M1A2 SEP (System Enhancement Package) Abrams MBT.[11] The M829A4 is intended to defeat the newest Russian Relikt explosive reactive armor (ERA), which detonates on radar command just before a KE penetrator hits it, (see Kontakt-5).

The M829A4 is a fifth-generation APFSDS-T cartridge consisting of 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.[12] Its propellant maintains consistent muzzle velocities across operational temperatures from −25 to 145 °F (−32 to 63 °C). 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.[5] On 20 July 2015, Orbital ATK announced that the M829E4 had passed First Article Acceptance Testing and was entering production.[13] 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.[14]

References[edit]

  1. ^ a b c d "M256 120mm Smoothbore Gun". Gary's Combat Vehicle Reference Guide. Archived from the original on 22 October 2013. Retrieved 5 July 2014. 
  2. ^ "120 mm M829 APFSDS-T cartridge (United States), Tank and anti-tank guns". Jane's Information Group. Archived from the original on 18 May 2011. Retrieved 2 January 2012. 
  3. ^ "120mm Tank Gun KE Ammunition". Defense Update. 2006-11-22. Retrieved 2007-09-03. 
  4. ^ Zaloga., Steven J. (18 August 2009). M1 Abrams vs T-72 Ural: Operation Desert Storm 1991 (Duel). Osprey Publishing. p. 34. ISBN 978-1-84603-407-7. 
  5. ^ a b "US to demilitarise 78,000 depleted uranium tank rounds". Campaign Against Depleted Uranium. 9 May 2014. Retrieved 5 July 2014. 
  6. ^ "M829E3 120mm Armor-Piercing Fin-Stabilized Discarding Sabot- Tracer (APFSDS-T) Cartridge" (PDF). 
  7. ^ Unclassified and declassified munitions technology may still remain "export controlled" information, per ITAR, meaning more specific technical details are unavailable for public release, and no credible reference can be provided.
  8. ^ "120mm Tank Gun KE Ammunition". Defense Update. 2006-11-22. Retrieved 2007-09-03. 
  9. ^ China Builds the World's Fastest Tank Gun, Then Tries to Hide It - Popsci.com, 19 June 2015
  10. ^ "Future tank round" (PDF). Retrieved 5 November 2010. 
  11. ^ ATK To Develop M829A4 120mm Advanced Kinetic Energy Round for M1A2 SEP Tank - Deagel.com, 11 July 2011
  12. ^ Fifth generation Army tank cartridge reports loudly for duty - Army.mil, 18 April 2014
  13. ^ Orbital ATK's M892E4 Advanced Kinetic Energy 120mm tank cartridge enters into production - Armyrecognition.com, 22 July 2015
  14. ^ Orbital ATK has received $105 million domestic and international contracts for ammunition - Armyrecognition.com, 13 October 2015

External links[edit]