Gun barrel
For firearms, a barrel was a hollow tube which served as the part of the weapon where a projectile was propelled from.

In 2366, Jean-Luc Picard agreed with Data that terrorism could be an effective way to promote political change, but Picard never subscribed to the theory that political power came from the barrel of a gun. ()

See also 
 Gun barrel rod
 Phaser emitter
 Rifled barrel

External link 
 

Weapon components