The casing was partitioned, and through this opening, the barrel shaft was journaled. In front of the casing was a cam with spiral surfaces. The cam imparted a reciprocating motion to the locks when the gun rotated. Also in the casing was a cocking ring with projections to cock and fire the gun. Each barrel had a single lock, working in the lock cylinder on a line with the barrel. The lock cylinder was encased and joined to the frame. Early models had a fibrous matting stuffed in among the barrels, which could be soaked with water to cool the barrels down. Later models eliminated the matting-filled barrels as being unnecessary.