OVERVIEW: 125mm High-Explosive Anti-Tank (HEAT) ammunition is designed to defeat armored vehicles by using a shaped charge to concentrate explosive force into a high-velocity jet capable of penetrating modern armor. These rounds provide effective anti-armor performance regardless of range, unlike kinetic energy penetrators.

DETAILS: HEAT rounds fired from 125mm smoothbore guns consist of a full-caliber projectile containing a conical shaped charge lined with metal. Upon impact, the explosive forms a focused jet capable of penetrating rolled homogeneous armor, composite armor, and, in tandem-charge variants, even explosive reactive armor (ERA). These rounds often include a tracer element and may also provide secondary fragmentation and blast effects against bunkers or soft targets. HEAT munitions do not rely on velocity for penetration, making them effective even at lower speeds or longer ranges.

ROLE SUMMARY:
Category: Tank Gun Ammunition
Primary Use: Anti-armor
Function: Armor penetration via shaped charge jet
Strong Against: Armored vehicles, bunkers, reinforced structures, vehicles with ERA
Weak Against: Active protection systems, spaced armor traps, soft targets, infantry in cover
Platform: MBTs with 125mm smoothbore guns
Integration: Compatible with 2A46, 2A46M, and 2A82 series tank guns

SOURCE:
Janes Ammunition Handbook
https://en.wikipedia.org/wiki/125_mm_smoothbore_ammunition