Made it from a D2 steel round bar, sat down with the CAD guy and put everything together, dimensionally and then all machining was done on a Haas VMC. Later I merely 'seasoned' it by running a few dozen fired plastic hulls trimmed to 2.5" to leave the walls straight and used a little Flitz mixed with oil smeared over the hull, perfect polishing tool for the insides and to get the crimp knuckles inside all shiny and smooth! Now paper or plastic, no problems!!