Which M2 machine gun round combines functions of an armor piercing bullet and incendiary bullet?

The M8 API cartridge is specifically designed to fulfill the dual role of armor-piercing and incendiary capabilities. It features a steel-core projectile that is capable of penetrating armored targets while simultaneously incorporating an incendiary element that ignites upon impact. This innovative design allows the round to effectively combat both hard targets and soft targets, making it versatile in various combat scenarios.

The M2 Ball cartridge primarily serves as a standard ball ammunition for training and does not have armor-piercing or incendiary properties. The M6 AP cartridge is focused entirely on armor-piercing capabilities without the incendiary function, and the M3 Dummy cartridge serves as a training round devoid of any live ammunition function. Thus, the M8 API cartridge stands out as the most effective choice for combining these critical functions.