IN ONE CRUCIAL STEP, THE HORNADY DELUXE 4-BLADE CHAMFER-DEBURRING TOOL REMOVES IMPERFECTIONS FROM THE CASE MOUTH OF YOUR CARTRIDGES. The Hornady Deluxe 4-Blade Chamfer-Deburring Tool is a two fold tool with the ability to chamfer the inside and deburr the outside edge trimmer on new cartridge cases. Why is this important? In removing the case mouth imperfections you increase seating consistency and reduce the chance of shaving material offa bullet when it is being seated.