Wikipedia
Expanding bullets are projectiles designed to expand on impact, increasing in diameter to limit penetration and/or produce a larger diameter wound for faster incapacitation. Therefore, they are used for hunting and by some police departments, but are generally prohibited for use in war. Two typical designs are the hollow-point bullet and the soft-point bullet.
Usage examples of "expanding bullet".
An expanding bullet had struck Pingo in the back, between the shoulder blades, and emerged with explosive force from his chest, leaving a gaping hole more than six inches across.
The disadvantage of a heavy-caliber expanding bullet is that it will spoil the meat (in the case of a boar) or spoil the hide (in the case of a tiger).
Now he wrapped the bullet in the patch so that, when the rifle fired, the expanding bullet would force the leather into the barrel’.