In TT it is very important to utilize multiple types of ammunition based on the multiple types of opponents you will face on the battlefield.
AP[]
AP is the default ammo that most tanks start with. It has medium penetration and medium damage. Most will use it till they can afford APDS or HEAT. It is also the basic ammo for tanks and it provides standard damage,penetration and accuracy. Though it's not the best.
Damage[]
This round does the least damage to opponents.
Accuracy[]
This round is very accurate at both short and long distance, but due to its low damage it is rarely used in higher ranking matches.
APDS[]
(Armor Piercing Discarding Sabot) is a high penetration, low to medium damage round used most often in higher level matches. This shell is very accurate and it is not restricted by spaced armor making it very effective versus low HP but high armor tanks with spaced armor however do not use it against a high HP low armor tanks or it will be very much useless.
Damage[]
APDS is best used against tanks with higher armor and HEAT countermeasures such as spaced armor and reactive armor. It doesn't seem to do a lot of damage in tanks with low damage stats. This makes HEAT more popular in lower level matches.
Accuracy[]
This round is a bit more accurate at long range than all the others.
HE[]
HE rounds are slightly more accurate than HEAT rounds, but less accurate than AP or APDS.
Damage[]
The most damage can be dealt by a direct hit, but it's still not too much. It's best used aganist hidden low armor targets like the PT-76, AMX-13, Ontos, M270 MLRS, or TOS-1.
Best chance of making heavy damage using an HE round is by using artillery, or if you are sniping it is a good round to use for spread damage, that way it can draw out the enemy
The FV101 Scorpion is known to do devastating damage with HE rounds, sometimes even damaging the enemy by 100+. The combination of speed and accuracy make it a real threat to other vehicles, but just like other light tanks, is also destroyed by HE rounds (due to it's low armor).
Accuracy[]
HE rounds are slightly more accurate than HEAT rounds, but less accurate than AP or APDS.
HEAT[]
HEAT (High Explosive Anti Tank) ammo has low accuracy and high damage. Popular in the low to medium level games, It has less effectiveness against spaced and reactive armored tanks.
Damage[]
As stated before, the HEAT round does higher damage than the other ammo choices, but ONLY against tanks without HEAT countermeasures. Remember which tanks have these, and choosing the right ammo is super easy.
The best chance of using a HEAT round against a high armor tank, is to hit the tracks, or hit the rear armor where it is much weaker. The upgrades for this shell are relatively very expensive compared to other shells.
Accuracy[]
Without gun accuracy upgrades, this round is a scatter-shot at longer range. However, if one knows how to use it, it's a devastatingly effective sniping round.
ATM[]
ATMs are anti-tank missiles with a HEAT warhead. They have excellent penetration, lock on capability, and can be fired from cover. As of 20a the ATM can only be fired a limited number of times, and is the only ammo with this limitation.
They have limited range and cannot be used for close combat. Active-Protection System decreases the chance of penetration. Smoke Grenades hide your tank and decrease the chance of a hit. Spaced armor affects the ATM the same way it affects a HEAT warhead.
Players on the forum have been debating whether to have it be unlimited or not. There have also been suggestions to raise the amount of atms each player can get at a time.
Damage[]
Damage with ATM's varies from tank to tank but it does usually deliver very high damage on impact.
Accuracy[]
ATM require you to lock onto the target first before firing. This can take valuable seconds to track a moving target. Once locked on the missile is fired, no further aiming is required. It will home in on its target however its turning capabilities are limited and if the enemy moves behind an obstruction it will collide.
Rocket[]
The rocket is a type of artillery ammo only usable by the TOS-1 and M270 MLRS. It appears to have more splash damage then the standard the HE shell. Remember, they are rockets, not missiles.
Damage[]
Damage is very high on rockets (similar to ATM) with the difference of splash damage.
Accuracy[]
These are aimed manually by the player.
Mine[]
Mines are a type of ammunition that is passive. The player selects the mines, and automatically places them on the ground. When an enemy vehicle drives over the mines, they will be either severely damaged or destroyed.
Damage[]
Damage is very high regardless of how much reactive armor you have, if u have a trophy system, and even how thick your armor is, though the damage varies based on how high the level on the vehicle is.