ENARM Pentagun

The Pentagun is a five-round shotgun manufactured by the Brazilian firm ENARM. It has a revolver-type cylinder and could be fired in double action-only.
The Pentagun's design prevented the gas venting that occurs between the cylinder and barrel on typical revolvers, by means of a movable barrel, which was pulled just prior to firing 1.5mm backwards into the corresponding recesses in the cylinder. The shotgun utilizes a straight-line configuration in order to minimize muzzle rise when firing.