Which of the following is NOT a component of a round?

The trigger is not a component of a round. A round is made up of three primary components: the cartridge case, the bullet, and the primer.

The cartridge case is the container that holds all the other components together and provides a means to chamber the round in a firearm. The bullet is the projectile that is expelled from the barrel when the round is fired. The primer is a small explosive device located at the base of the cartridge case that ignites the gunpowder when struck by the firing pin, leading to the discharge of the bullet.

In contrast, the trigger is a mechanism in the firearm that allows the shooter to initiate the firing process. While the trigger is essential for firing the round, it is not a part of the round itself, which is specifically the ammunition cartridge that is loaded into the firearm.