| Silencers |
Muzzle
brakes |
Compensators |
Flash
Suppressors |
Being a projectile, a bullet's trajectory follows a parabolic path. The line of sight crosses the trajectory at two distances. The distances at which the line of sight cross the bullet's trajectory are known as the weapon's "zero."
In the figure above, when fired, the bullet exits the barrel of the gun with a certain velocity, known as the "muzzle velocity." The vertical component of the velocity vector (y-axis) experiences an acceleration due to gravity in the negative y-direction. "Bullet drop" is the distance the trajectory lays below the centerline of the bore. The horizontal component of the velocity vector (x-axis) experiences acceleration in the negative x-direction due to drag while the bullet flies through the air. This drag causes increasing bullet drop and therefore is more noticeable further down range.