An improved barrel clamp assembly for a multi-barreled minigun includes a barrel clamp tube having a front end, a rear end, and a plurality of longitudinal openings extending between the front end and the rear end. An impeller is mounted in the barrel clamp tube between the tube front end and the tube rear end. The impeller includes a plurality of impeller blades that are spaced around a periphery of the impeller and that project forward from a rear flange portion of the impeller and the impeller blades define a plurality of air channels. A barrel assembly includes the barrel clamp tube, a flash suppressor mounted to the front end of the barrel clamp tube, and a barrel clamp co liar mounted to the rear end of the barrel clamp tube. The impeller is mounted to the barrel clamp tube between the flash suppressor and the barrel clamp collar.