Slide cover plates, and handguns including the slide cover plates, where the slide cover plates include a primary cover plate portion and a sealing cover plate portion that is movably coupled to the primary cover plate portion so that the sealing cover plate portion has an open position and a closed position, and when in its closed position the slide cover plate provides protection for the interior of the handgun, and when in its open position the slide cover plate does not interfere with the forward movement of the pistol slide.