here is a link to see what the inside of a bullet or round might look like… The “primer” is the part that gets hit when you pull back the trigger on a gun, igniting the inside of the bullet, pushing out the projectile. After you pull the trigger, it all happens so fast, but there are several different things that happen after you pull back on a trigger, depending on what weapon you’re using. But in general, pull the trigger, it hits the primer, and it does the rest, just make sure the weapon is pointed away from anyone, and down range towards a target. If you’re shooting a pistol, it’s a good idea to wear eye protection because sometimes the bullet casing comes back at you.