SAECO Bullet Moulds All SAECO Black Powder Cartridge bullet moulds are machined from solid cast iron blocks one cavity at a time. Using the same cutting tool (cherrie) for each cavity on digital equipment guarantees that each cavity dupicates the previous one. You don't need to pay a premium for matched cavities. SAECO even developed its own blend of copper alloyed pearlitic cast iron for tight grain structure, dimensional stability and extended life. The steel spure plates are held firm against the mould blocks by high tempeture spring washers to insure uniform bullets with square bases. Mould handles(sold separatly) are ducktile iron castings with solid hardwood grips.