The M829 is an American Armor-Piercing, Fin-Stabilized, Discarding Sabot (APFSDS) tank round designed specifically for the 120 mm M256 main gun on the 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 performance against nearly all known types of tank armour. The penetrator is hold in place by the sabot during the acceleration in the gun barrel.
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The penetrator is made of depleted uranium alloys which offer good performance against tank armour, except the newest generations of explosive reactive armour (ERA).
The M829 has a ballistic cap and five tail fins made of aluminum; it also has a long carbon fiber sabot. The sabot holds the sub-caliber round in place in the barrel and breaks off into five "petals" as the round leaves the gun tube. The propulsion system uses an obturating case base with a semi-combustible wall. It has a total weight of 41.1 pounds and is utilizing a 615 mm (24.2 in) DU penetrator, which will reach because of 8.1 kg (18 lb) of JA-2 propellant a muzzle velocity of 1,670 metres per second (5,500 ft/s).[1] Maximum effective range is 3,000 m (9,800 ft).[1] According to Jane's the M829 is capable of penetrating 540 mm of steel armour (RHA) at 2,000 m (6,600 ft) range.[1] It is no longer in production and has been succeeded by the M829A1, M829A2, and M829A3.
The M829A1 (nicknamed the "Silver Bullet" by Operation Desert Storm tank crews) has proven itself against the Iraqi armour during Operation Desert Storm, however it's effectivity has been reduced by modern reactive armor like the Russian Kontakt-5, which led to the rapid development of the M829A2 and later the M829A3 (this in turn led to the development of the new Russian 'Relikt' ERA). The round weighs 20.9 kg (46 lb) and has an overall length of 984 mm (38.7 in). 7.9 kg (17 lb) of JA 19 propellant create a chamber pressure of 5,600 bar which leads to a muzzle velocity 1,575 m/s (5,170 ft/s). The 684 mm (26.9 in) penetrator weighs together with the sabot 9 kg (20 lb). The weight of the penetrator alone is 4.6 kg (10 lb). The effective target range is 3,000 m (3,300 yd).[2] Point-blank the M829A1 is estimated to penetrate 670 mm of steel armour, which decreases to 620 mm at 1,000 m (3,300 ft) and 570 mm at 2,000 m (6,600 ft).[3] At 4,000 m (13,000 ft) it is still believed to penetrate 460 mm of steel armour.[3]
The M829A2 APFSDS is a third-generation anti-tank round based on the M829 penetrator and designed for the 120 mm M256 main gun in the M1A1 (or later) Abrams main battle tank. The M829A2 was rapidly developed to have the capability to destroy tanks equipped with Kontakt-5 reactive armor. The M829A2 has several improvements over the M829A1, including: a longer depleted uranium penetrating rod than previous designs, giving it improved performance over previous types of anti-tank rounds; better manufacturing processes for the penetrator; and a partially cut propelling charge to allow it to be more energetic while loading like a stick charge. The M829A2 was also the first APFSDS round to use carbon fiber sabot petals, reducing the weight of the overall round and allowing for the larger penetrator. Combined these features boost its muzzle velocity to 1,680 m/s (5,500 ft/s), while operating at slightly lower pressure. The M829A2 entered service in the United States Army in 1993.
The M829A3 is a 120 mm APFSDS round developed from the M829A2 round. It completed type classification standard in March 2003 and is currently in full rate production for the US Army.
Very little is known about the round. The M829A3 uses a more efficient propellant, RPD-380, giving it a boost in muzzle velocity. The M829A3 round has a total weight of 22.3 kg (49 lb) kg and length of 892 mm (35.1 in). It uses 8.1 kg (18 lb) kg of RPD-380 stick propellant, accelerating a 10 kg (22 lb) kg long depleted uranium rod penetrator believed to be about 920 mm (36 in) long and 20 mm (0.79 in) in diameter to a muzzle velocity of 1,555 m/s (5,100 ft/s). The sabot is built of composite material.[4]
The E4 variant is under development by General Dynamics Ordnance and Tactical Systems and Alliant Techsystems. One contractor will be downselected.[5]