What component seals the powder away from the shot in shotshell reloading?

The component that seals the powder away from the shot in shotshell reloading is the wads. Wads serve multiple purposes in shotshells: they create a seal that prevents the gunpowder from escaping into the shot column, which is critical for maintaining proper pressure and consistency of the shot charge. This seal is important during ignition, as it allows for efficient combustion of the powder and ensures that the gas generated by the burning powder is directed properly to propel the shot down the barrel.

In addition to sealing the powder, wads also cushion the shot to reduce deformation and can help with shot spread when the shotshell is fired. While the shot itself, the primer, and the shot cup are also important components of a shotshell, they do not provide the sealing function that wads do. The ball of shot is the projectile that exits the shotgun barrel, the primer initiates the ignition of the powder, and the shot cup is another part of the wad system that holds the shot. Hence, wads are the critical element responsible for sealing the powder from the shot in the reloading process.