Shot grouping

Two shot groupings obtained with different firearms at different distances.
The group on the left measures about 13 mm and was fired at about 45 meters, which equals 13 mm/45 m = 0.29 mils (1⁄2 in group at 50 yards, approx. 1.047′×50/100 = 0.524′).
The group on the right measures about 7 mm and was fired at about 90 meters, which equals 7 mm/90 m = 0.08 mils (0.3 in group at 100 yards, approx. 1.047′×0.3 = 0.314′).

In shooting sports, a shot grouping, or simply group, is the collective pattern of projectile impacts on a target from multiple consecutive shots taken in one shooting session. The tightness of the grouping (the proximity of all the shots to each other) is a measure of the precision of a weapon, and a measure of the shooter's consistency and skill.^[1][2] On the other hand, the grouping displacement (the distance between the calculated group center and the intended point of aim) is a measure of accuracy.

Tightness of shot groupings are calculated by measuring the maximum distance between any two bullet holes on the target (center-to-center) in length measurements such as millimeters or inches. Often that measurement is converted into angular measurements such as milliradians ("mils" or "mrads") or minutes of angle (MOAs), which expresses the size of shot scatter regardless of the target distance. Thus, by using angular measurements, one can reliably compare the relative tightness of shot groupings fired at different distances.