Abrams have only rarely been knocked out by direct fire from other tanks. They have fallen prey to artillery and AGTMs. The armor on the sides of the turret, which slants, presents a thicker surface through which a projectile must travel. In addition, the Abrams uses Cobham armor, interlocking layers of different materials that cause a projectile to alternately expand and then get smashed by harder surfaces. RPG-7s fire at the sides of tanks since they have no proximity fuses, at least on the regular projectiles, and have no hope of penetrating the armor although they might be able to blow off treads, prismatic sights, or engine covers.

Shaped charge explosives are kind of terrifying, since they're a cross between a kaboom and a cannon.