Which feature is not commonly associated with shotgun shells?

In the context of shotgun shells, the gauge, diameter, and length are all essential specifications that define the shell and its compatibility with shotgun firearm. Gauge refers to the size of the shotgun shell and is a measurement defined by the number of lead balls of the bore diameter that equal one pound. This measurement determines the internal diameter of the funnel and directly affects which shotguns the shell can be used in.

The diameter is directly associated with the gauge since it reflects the actual measurement of the shell's bore. Additionally, the length of the shell is key because it affects the shell's capacity and operation within different shotgun models. Shotgun shells typically come in various lengths such as 2.75 inches, 3 inches, or 3.5 inches, impacting the amount of powder and shot contained within.

While weight does play a role in shotgun ammunition, particularly in terms of the load of pellets or shot used, it is not a standardized feature across different types of shotgun shells in the same way that gauge, diameter, and length are. Therefore, weight is not a commonly referenced characteristic when discussing shotgun shells, making it the least associated feature among the options provided.