Image Number 4 for United States Patent #7743706.
A bullet for cleaning/scouring the interior surface of a gun barrel including a jacket section on a rear end and joined to a projectile section on the other end forming a chamber containing a cleaning liquid. An array of brushes is positioned on the outside surface of the forward wall of the projectile section. An explosive cake is positioned against the rear end of the jacket section. A piston disk is positioned against the cake. When the cake is detonated, the disk first expels fluid from the chamber and against the interior wall of the barrel. Then the disk forces the forward wall to spread out so that the brushes on the forward wall come into contact with the interior surface of the gun barrel.