Sighting in

The principle of sighting-in is to shift the line of aim until it intersects the parabolic projectile trajectory at a designated point of reference, so when the gun is fired in the future (provided there is reliable precision) it will repeatably hit where it aims at identical distances of that designated point.

Because when using a telescopic sight, the crosshair lines geometrically resemble the X- and Y-axis of the Cartesian coordinate system where the reticle center is analogous to the origin point (i.e. coordinate [0,0]), the designated sighting-in point is known as a zero, and the act of sighting-in is therefore also called zeroing.

Bullets discharged from a firearm immobilized in a device such as a Mann rest may not always land in precisely the same spot.

Groups should not be confused with the patterns traditionally used to describe the positioning of a specified percentage of the multiple pellets from an individual shotgun shell.

Some targets include a faint grid for easier measurement of horizontal and vertical distance from point of aim.

[5] Other stable shooting positions include sitting on the ground while leaning against a tree or structure and resting the firearm on an arm supported by the knees.

The sights are examined prior to firing to be certain they are firmly fastened to the firearm and are not loose or moving between shots.