As the stab leaves the cradle vault it begins to disperse in the air. The resulting cloud of pellets is known as the conjecture pattern. The ideal pattern would be a circle with an even distribution of opening 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 sometimes measured by firing at a 30 inch (76cm) diameter circle on a larger 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 duty silhouette will fit and not cover 3 or enhanced holes is considered a potential problem.

A constriction in the end of the cask known as the choke is worn to tailor the pattern for contrastive purposes. Chokes may either be formed as component of the barrel at the era of manufacture, by squeezing the confine of the bore down over a mandrel, or by threading the barrel and screwing in an interchangeable choke tube. The choke commonly consists of a conical section that smoothly tapers from the bore diameter down to the choke diameter, followed by a cylindrical section of the choke diameter. Briley Manufacturing, a head maker of interchangeable shotgun chokes, uses a conical portion about 3 times the bore diameter in length, so the fling is gradually squeezed down with minimal deformation. The cylindrical section is shorter, regularly 0.6 to 0.75 inches (15 to 19 mm). There is no admirable mathematical model that describes how chokes work, directing the design and manufacture for chokes more craft than science. The use of interchangeable chokes has made it easy to tune the performance of a Shotguns given combination of shotgun and shotshell to achieve the desired performance.