HE (high Explosive) ammo has low penetration and medium damage. They are great for enemies behind cover because they cause splash damage like Artillery. They all round aren't that good compared to the other shells.
HE rounds are slightly more accurate than HEAT rounds, but less accurate than AP or APDS.
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
An FV101 Scorpion could deal 100+ damage with an HE round so if u want to use this small tank to chase somebody and u cant aim perfectly so u can just hit the ground near it.