Modern tanks tend to have main gun barrels which are coated in thermal lagging.
This material is intended to protect the weapon from small differences in temperature (as might be caused by being parked under a desert sun). The resulting barrel deflection can cause serious inaccuracy when the gun is fired.
Today’s invention offers a way to attack such a tank so as to disable the thermal lagging, and render the machine largely useless, but without harming the crew.
A low velocity shell, containing a thermite core (of the type used in hand grenades or incendiaries) and a large number of eg ball bearings, would be fired at the front of the turret.
As a means of tank destruction, this would be completely futile, but the shrapnel would shred the thermal lagging and the thermite would then damage the exposed gun barrel, by intense, local heating.
