Page "Shotgun" Paragraph 11

Shot, small and round and delivered without spin, is ballistically inefficient.

As the shot leaves the barrel it begins to disperse in the air.

The resulting cloud of pellets is known as the shot pattern, or shotgun shot spread.

The ideal pattern would be a circle with an even distribution of shot throughout, with a density sufficient to ensure enough pellets will intersect the target to achieve the desired result, such as a kill when hunting or a break when shooting clay targets.

In reality the pattern is closer to a Gaussian, or normal distribution, with a higher density in the center that tapers off at the edges.

Patterns are usually measured by firing at a 30 inch ( 76 cm ) diameter circle on a large sheet of paper placed at varying distances.

The hits inside the circle are counted, and compared to the total number of pellets, and the density of the pattern inside the circle is examined.

An " ideal " pattern would put nearly 100 % of the pellets in the circle and would have no voids — any region where a target silhouette will fit and not cover 3 or more holes is considered a potential problem.