India has ordered 66,000 Russian 3VBM17 APFSDS (Armor Piercing Fin Stabilized Discarding Sabot) shells for the 125mm guns on their T-90 tanks. Each of these shells will cost $6,556. The 3VBM17 entered service in 1986, weighs 20.4 kg (45 pounds) and employs a 4.85 kg (10.7 pound) tungsten penetrator that will go through 450mm of steel. The penetrator and its sabot leaves the gun at 1,700 meters (5,610 feet) a second. India wanted to buy an Israeli APFSDS shell but the supplier got tied up in an Indian anti-corruption investigation so, rather than wait for that to blow over, and because the army was running low on these shells, they went for the Russian supplier. The Israeli shell would have been more reliable and penetrate over 20 percent more armor, but considering the tanks likely opponents (China and Pakistan) have, the 3VBM17 is adequate and a little cheaper.
Most modern 120/125mm tank guns fire a shell that uses a smaller 25mm “penetrator.” The 25mm rod of tungsten (or depleted uranium) is surrounded by a “sabot” that falls away once the shell clears the barrel. This gives the penetrator higher velocity and penetrating power. This is the most expensive type of 120/125mm shell and already comes in several variants. There is APDS (Armor Piercing Discarding Sabot) and APFSDS (Armor Piercing Fin Stabilized Discarding Sabot, for smooth bore guns). The armor piercing element of discarding sabot rounds is less than half the diameter of the shell and made of very expensive, high density metal. Its smaller size enables it to hit the target at very high speeds, up to 1,900 meters (6,270 feet) a second. This is the most common type of anti-tank shell and is constantly being improved.
India uses other times of 125mm ammo as well. In 2013 India obtained a manufacturing license to build 15,000 Russian Invar anti-tank missiles for their T-90s. India has earlier purchased 10,000 of these missiles from Russia (that were built in Russia) and with the manufacturing license the average cost will be about $2,000 per missile. Buying the missiles from Russia costs nearly $40,000 per missile, while manufacturing in India can cut that by nearly 30 percent, making the $2,000 per missile license a good deal. The Invar 9M119M1 (Invar-M) is fired from the 125mm gun, like a shell, but operates like a guided missile. The 17.2 kg (37.8 pound) missile is 680mm (26.7 inches) long and has pop-out fins (with a 250mm/9 inch span) that aid in guidance (laser beam riding, controlled by the tank gunner). The missile has a max range of 5,000 meters at a speed of 350 meters a second (14 seconds max flight time). The Invar enables the tank to hit targets at twice the range of the 125mm shells. The tandem warhead can penetrate up to 900mm of armor (35.4 inches), twice what the 3VBM17 can. Invar has been around for two decades and India is buying the latest version.
India expects to have about 1,400 T-90s by the end of the decade. The first T-90 entered service in 1993, and India is the largest user. The T-90 is basically an upgraded T-72, which India already builds under license. The T-90 weighs about 15 percent more than the 41 ton T-72. The T-90 has a better fire control system, night vision that is good out to about 1,500 meters, and electronic countermeasures against anti-tank missiles. The autoloader, which often failed in the T-72, is more reliable and that makes the three man crew (commander, gunner, driver) more effective. The T-90 has ERA (Explosive Reactive Armor) in addition to its composite armor.
The T-90 is not as lively as the T-72 and is actually slower on the battlefield than the U.S. M-1 (which has a horsepower to weight ratio of 24:1, compared to only 18:1 for the T-90). The 125mm gun of the T-90 is basically the same as the T-72. However, if you use better ammo, you stand a chance against top rated tanks like the M-1. But that is not what India expects to face. The most likely opponent is Pakistan, which is largely equipped with 1950s era T-55s (actually the Chinese T-59 copy). The Pakistanis also have 700 or so older T-72 type tanks (Chinese T-69 and Ukrainian T-80), but these would be outclassed by the T-90. India plans to have 21 tank battalions ("regiments" in the Indian army) of T-90s (with 62 tanks each) by 2020. Actually, each battalion only has 45 tanks going into combat. The other 17 are for training and replacements.