OVERVIEW: The 122mm High-Explosive Anti-Tank (HEAT) round is a shaped-charge munition designed for use with Soviet-era 122mm guns, primarily for defeating armored vehicles through focused explosive energy. It was developed to provide anti-armor capability to artillery and assault gun platforms firing low-velocity shells.

DETAILS: The 122mm HEAT round utilizes a shaped charge with a metal liner to form a high-velocity penetration jet upon impact, enabling it to pierce armor independently of distance. It was employed primarily by vehicles equipped with the 122mm D-25T gun, such as the IS-2 and IS-3 heavy tanks, as well as the ISU-122 self-propelled gun. These rounds were fin-stabilized and generally fired at lower velocities compared to kinetic penetrators, relying on the shaped charge effect rather than impact energy. Typical penetration performance was around 200–250 mm of rolled homogeneous armor, sufficient for the battlefield threats of the mid-20th century. Although obsolete against modern main battle tanks, it remained useful against medium armor, bunkers, and fortified positions.

ROLE SUMMARY:
Category: Tank/Artillery Gun Ammunition
Primary Use: Anti-armor
Function: Armor penetration via shaped-charge jet
Strong Against: Armored vehicles of WWII and early Cold War, field fortifications
Weak Against: Modern composite armor, ERA, APS-equipped vehicles
Platform: IS-2, IS-3 heavy tanks; ISU-122 self-propelled gun (D-25T 122mm gun)
Integration: Designed for 122mm D-25T and similar guns; incompatible with high-velocity or modern smoothbore tank guns

SOURCE:
Janes Ammunition Handbook ; U.S. Army Foreign Materiel Intelligence Reports ; Russian Ministry of Defence Archives ; https://en.wikipedia.org/wiki/D-25T