What component is primarily responsible for propelling a bullet out of the barrel?

The component primarily responsible for propelling a bullet out of the barrel is the propellant and the expanding gases created when the propellant ignites. When the trigger is pulled, the firing pin strikes the primer, which ignites the powder within the cartridge. This combustion produces a rapid expansion of gases, generating high pressure that forces the bullet down the barrel and out of the firearm.

This process relies on the chemical energy stored in the propellant, transforming it into kinetic energy that drives the bullet forward. The effectiveness and speed of this process are critical to the bullet's performance. The other elements, such as bullet weight, barrel length, and mechanisms like levers, may influence the accuracy and velocity of the bullet but are not the primary force propelling it from the barrel.