Even small caliber bullet wounds to the liver are most times fatal.
One buckshot pellet in a deer’s liver will kill them graveyard dead...after they go 100 - 300 yds, most times without a blood trail.
It’s why many states have outlawed buckshot, it kills without little sign to follow.
There are different sizes of buckshot but the most commonly used is 00 buck. Every pellet of 00 buckshot is .30 caliber in diameter which is the typical caliber of a rifle bullet used for deer hunting.
Not exactly small caliber in the context of deer hunting.