Which component is found in shotgun shells but not in rifle cartridges?

The component that is found in shotgun shells but not in rifle cartridges is the wad. The wad serves a unique function in shotgun shells, acting as a barrier between the propellant and the shot or slug, helping to contain the gases produced by the burning powder and ensuring that the shot or projectile is propelled effectively toward the target. It also helps to protect the shot from deformation during firing and can aid in controlling the shot pattern.

In shotgun shells, the wad is typically made of materials like plastic or cardboard and is integral to the shell's design. Conversely, rifle cartridges do not require a wad because they use a single projectile (the bullet) rather than multiple projectiles or shot. The design of rifle cartridges, which combines the bullet, powder, and primer directly within the casing, eliminates the need for a wad, as the functioning principles differ significantly from those of shotguns.