Beating Heart Six-Shooter

A big, chunky revolver, break-apart Old West style. The cylinder, however, is missing. In its place, held to the frame of the pistol with translucent tissues and vessels crawling into the action of the gun, is a small but realistic beating human heart.

On each beat it builds up a certain energy in the gun, releasing it as a powerful shot, then can fire again regularly. (Basically gains 1 charge per turn, max 6, can spend charges to fire; d6s dealt by the pistol are equal to the charges spent).

Looks like a LeMat or a Colt Walker.