Grouping (firearms)

In shooting sports, a shot grouping, or simply grouping, is the placement of multiple shots on a target, 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.

For firearms that shoot one round at a time, a shot grouping test can be used to measure the accuracy of the shooting system: the weapon's mechanical precision and the uniformity of the ammunition. The weapon is fixed into position on a test mount, and aimed at a target. Multiple shots using rounds from the same type and batch are fired to observe how the weapon groups the shots. If a person holds the weapon and shoots it, the grouping measures the combination of the person's skill and the weapon's accuracy.

In shotgun shooting, the grouping is also called the pattern. The pattern is the spread of shot from a single shotgun shell, measured as the smallest circle containing all the shots on the target. The barrel of a shotgun is designed to deliver a wide or narrow grouping, depending on the expected use. Shooting at close range indicates a cylinder bore barrel to deliver a wide grouping, while for hunting at longer distances such as 50 yards or meters, a choke is recommended for a tighter grouping.

In archery, a shot grouping is the result of one person shooting multiple arrows at a target. A tight grouping indicates consistency in form.

Mean point of impact (MPI) is the calculated center of the grouping, which is the average center of all the shots, and is not necessarily located at a hole in the target. The size of the grouping is described as the smallest circle containing all the shots.

A "flier" is a shot from the same shooting session that is farther from the general shot group, considered to be outside of the grouping. Such shots may be the result of an unexpected gust of wind, a muscular flinch of the person shooting, or it may indicate a problem with the firearm mechanism. Rarely, it may indicate inconsistency in the ammunition. Single fliers may be discounted when evaluating a grouping, but if fliers occur often, then the problem should be traced to its origin.

While target shooting with a handgun, if a grouping is consistently off-center then the shooter is instructed to alter the body angle or the stance, rather than shifting the arm, wrist or hand, which should remain in position.

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