Looks like a lego guy at first.

The significant plumes of smoke generated when the weapon was fired indicate that it does not make use of commercial small arms ammunition propellant (‘smokeless powder’), and may instead use blackpowder or an alternative propellant. This makes the use of ‘separate-loading’ ammunition (i.e., propellant and projectile loaded separately into the weapon) more likely, as well as increasing the likelihood that the weapon was a muzzle-loading design—that is, loaded from the bore (‘front’ of the barrel), rather than the breech (‘rear’ of the barrel) of the firearm.

the weapon appears to use an electric firing mechanism. Images of the firearm show that an electrical wire passes through each endcap. …This high voltage creates a hot plasma arc between two conductive contacts that can be used to ignite flammable materials