Revolver
Double-action means that a cocking action separate from the trigger pull is not needed. Every trigger pull causes a complete cycle and a bullet is fired. This allows the gun to be carried uncocked. It also allows the gun to be drawn from the holster and fired using only the trigger. However, a double-action revolver has a longer and harder trigger pull. However, this drawback can also be viewed as a safety feature, as the gun is safer against accidental discharges from being dropped.